diff --git a/lix/libutil/config.cc b/lix/libutil/config.cc
index 7600df038..95a85b9ca 100644
--- a/lix/libutil/config.cc
+++ b/lix/libutil/config.cc
@@ -344,22 +344,11 @@ template<> std::string BaseSetting<StringSet>::to_string() const
 
 template<> ExperimentalFeatures BaseSetting<ExperimentalFeatures>::parse(const std::string & str, const ApplyConfigOptions & options) const
 {
-    auto warnDeprecated294 = [](std::once_flag & flag, std::string_view thing) {
-        std::call_once(flag, [&] {
-            warn(
-                "The %s experimental feature is deprecated and will be removed in Lix 2.94. "
-                "See https://git.lix.systems/lix-project/lix/issues/815 for more details.",
-                thing
-            );
-        });
-    };
-
     ExperimentalFeatures res{};
     for (auto & s : tokenizeString<StringSet>(str)) {
         if (auto thisXpFeature = parseExperimentalFeature(s); thisXpFeature) {
             if (*thisXpFeature == Xp::CaDerivations) {
-                static std::once_flag warned;
-                warnDeprecated294(warned, s);
+                throw Error("CA derivations are no longer supported");
             }
             res = res | thisXpFeature.value();
         } else
diff --git a/tests/functional/build-remote-content-addressed-floating.sh b/tests/functional/build-remote-content-addressed-floating.sh
deleted file mode 100644
index e83b42b41..000000000
--- a/tests/functional/build-remote-content-addressed-floating.sh
+++ /dev/null
@@ -1,9 +0,0 @@
-source common.sh
-
-file=build-hook-ca-floating.nix
-
-enableFeatures "ca-derivations"
-
-CONTENT_ADDRESSED=true
-
-source build-remote.sh
diff --git a/tests/functional/ca/build-cache.sh b/tests/functional/ca/build-cache.sh
deleted file mode 100755
index 9b3b61e87..000000000
--- a/tests/functional/ca/build-cache.sh
+++ /dev/null
@@ -1,51 +0,0 @@
-#!/usr/bin/env bash
-
-source common.sh
-
-# The substituters didn't work prior to this time.
-requireDaemonNewerThan "2.18.0pre20230808"
-
-drv=$(nix-instantiate ./content-addressed.nix -A rootCA --arg seed 1)^out
-nix derivation show "$drv" --arg seed 1
-
-buildAttr () {
-    local derivationPath=$1
-    local seedValue=$2
-    shift; shift
-    local args=("./content-addressed.nix" "-A" "$derivationPath" --arg seed "$seedValue" "--no-out-link")
-    args+=("$@")
-    nix-build "${args[@]}"
-}
-
-copyAttr () {
-    local derivationPath=$1
-    local seedValue=$2
-    shift; shift
-    local args=("-f" "./content-addressed.nix" "$derivationPath" --arg seed "$seedValue")
-    args+=("$@")
-    # Note: to copy CA derivations, we need to copy the realisations, which
-    # currently requires naming the installables, not just the derivation output
-    # path.
-    nix copy --to file://$cacheDir "${args[@]}"
-}
-
-testRemoteCacheFor () {
-    local derivationPath=$1
-    clearCache
-    copyAttr "$derivationPath" 1
-    clearStore
-    # Check nothing gets built.
-    buildAttr "$derivationPath" 1 --option substituters file://$cacheDir --no-require-sigs |& grepQuietInverse " will be built:"
-}
-
-testRemoteCache () {
-    testRemoteCacheFor rootCA
-    testRemoteCacheFor dependentCA
-    testRemoteCacheFor dependentNonCA
-    testRemoteCacheFor dependentFixedOutput
-    testRemoteCacheFor dependentForBuildCA
-    testRemoteCacheFor dependentForBuildNonCA
-}
-
-clearStore
-testRemoteCache
diff --git a/tests/functional/ca/build-dry.sh b/tests/functional/ca/build-dry.sh
deleted file mode 100644
index 7d4406e2f..000000000
--- a/tests/functional/ca/build-dry.sh
+++ /dev/null
@@ -1,5 +0,0 @@
-source common.sh
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-
-cd .. && source build-dry.sh
diff --git a/tests/functional/ca/build-with-garbage-path.sh b/tests/functional/ca/build-with-garbage-path.sh
deleted file mode 100755
index 884cd2802..000000000
--- a/tests/functional/ca/build-with-garbage-path.sh
+++ /dev/null
@@ -1,21 +0,0 @@
-#!/usr/bin/env bash
-
-# Regression test for https://github.com/NixOS/nix/issues/4858
-
-source common.sh
-
-requireDaemonNewerThan "2.4pre20210621"
-
-# Get the output path of `rootCA`, and put some garbage instead
-outPath="$(nix-build ./content-addressed.nix -A rootCA --no-out-link)"
-nix-store --delete $(nix-store -q --referrers-closure "$outPath")
-touch "$outPath"
-
-# The build should correctly remove the garbage and put the expected path instead
-nix-build ./content-addressed.nix -A rootCA --no-out-link
-
-# Rebuild it. This shouldn’t overwrite the existing path
-oldInode=$(stat -c '%i' "$outPath")
-nix-build ./content-addressed.nix -A rootCA --no-out-link --arg seed 2
-newInode=$(stat -c '%i' "$outPath")
-[[ "$oldInode" == "$newInode" ]]
diff --git a/tests/functional/ca/build.sh b/tests/functional/ca/build.sh
deleted file mode 100755
index e1a8a7625..000000000
--- a/tests/functional/ca/build.sh
+++ /dev/null
@@ -1,67 +0,0 @@
-#!/usr/bin/env bash
-
-source common.sh
-
-drv=$(nix-instantiate ./content-addressed.nix -A rootCA --arg seed 1)^out
-nix derivation show "$drv" --arg seed 1
-
-buildAttr () {
-    local derivationPath=$1
-    local seedValue=$2
-    shift; shift
-    local args=("./content-addressed.nix" "-A" "$derivationPath" --arg seed "$seedValue" "--no-out-link")
-    args+=("$@")
-    nix-build "${args[@]}"
-}
-
-testDeterministicCA () {
-    [[ $(buildAttr rootCA 1) = $(buildAttr rootCA 2) ]]
-}
-
-testCutoffFor () {
-    local out1 out2
-    out1=$(buildAttr $1 1)
-    # The seed only changes the root derivation, and not it's output, so the
-    # dependent derivations should only need to be built once.
-    buildAttr rootCA 2
-    out2=$(buildAttr $1 2 -j0)
-    test "$out1" == "$out2"
-}
-
-testCutoff () {
-    # Don't directly build dependentCA, that way we'll make sure we don't rely on
-    # dependent derivations always being already built.
-    #testDerivation dependentCA
-    testCutoffFor transitivelyDependentCA
-    testCutoffFor dependentNonCA
-    testCutoffFor dependentFixedOutput
-}
-
-testGC () {
-    nix-instantiate ./content-addressed.nix -A rootCA --arg seed 5
-    nix-collect-garbage --option keep-derivations true
-    clearStore
-    buildAttr rootCA 1 --out-link $TEST_ROOT/rootCA
-    nix-collect-garbage
-    buildAttr rootCA 1 -j0
-}
-
-testNixCommand () {
-    clearStore
-    nix build --file ./content-addressed.nix --no-link
-}
-
-# Regression test for https://github.com/NixOS/nix/issues/4775
-testNormalization () {
-    clearStore
-    outPath=$(buildAttr rootCA 1)
-    test "$(stat -c %Y $outPath)" -eq 1
-}
-
-clearStore
-testNormalization
-testDeterministicCA
-clearStore
-testCutoff
-testGC
-testNixCommand
diff --git a/tests/functional/ca/common.sh b/tests/functional/ca/common.sh
deleted file mode 100644
index b104b5a78..000000000
--- a/tests/functional/ca/common.sh
+++ /dev/null
@@ -1,5 +0,0 @@
-source ../common.sh
-
-enableFeatures "ca-derivations"
-
-restartDaemon
diff --git a/tests/functional/ca/concurrent-builds.sh b/tests/functional/ca/concurrent-builds.sh
deleted file mode 100755
index b442619e2..000000000
--- a/tests/functional/ca/concurrent-builds.sh
+++ /dev/null
@@ -1,18 +0,0 @@
-#!/usr/bin/env bash
-
-# Ensure that we can’t build twice the same derivation concurrently.
-# Regression test for https://github.com/NixOS/nix/issues/5029
-
-source common.sh
-
-buggyNeedLocalStore "For some reason, this deadlocks with the daemon"
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-
-clearStore
-
-for i in {0..5}; do
-    nix build --no-link --file ./racy.nix &
-done
-
-wait
diff --git a/tests/functional/ca/config.nix.in b/tests/functional/ca/config.nix.in
deleted file mode 120000
index af24ddb30..000000000
--- a/tests/functional/ca/config.nix.in
+++ /dev/null
@@ -1 +0,0 @@
-../config.nix.in
\ No newline at end of file
diff --git a/tests/functional/ca/content-addressed.nix b/tests/functional/ca/content-addressed.nix
deleted file mode 100644
index 2559c562f..000000000
--- a/tests/functional/ca/content-addressed.nix
+++ /dev/null
@@ -1,100 +0,0 @@
-with import ./config.nix;
-
-let mkCADerivation = args: mkDerivation ({
-    __contentAddressed = true;
-    outputHashMode = "recursive";
-    outputHashAlgo = "sha256";
-} // args);
-in
-
-{ seed ? 0 }:
-# A simple content-addressed derivation.
-# The derivation can be arbitrarily modified by passing a different `seed`,
-# but the output will always be the same
-rec {
-  rootLegacy = mkDerivation {
-    name = "simple-input-addressed";
-    buildCommand = ''
-      set -x
-      echo "Building a legacy derivation"
-      mkdir -p $out
-      echo "Hello World" > $out/hello
-    '';
-  };
-  rootCA = mkCADerivation {
-    name = "rootCA";
-    outputs = [ "out" "dev" "foo" ];
-    buildCommand = ''
-      echo "building a CA derivation"
-      echo "The seed is ${toString seed}"
-      mkdir -p $out
-      echo ${rootLegacy}/hello > $out/dep
-      ln -s $out $out/self
-      # test symlinks at root
-      ln -s $out $dev
-      ln -s $out $foo
-    '';
-  };
-  dependentCA = mkCADerivation {
-    name = "dependent";
-    buildCommand = ''
-      echo "building a dependent derivation"
-      mkdir -p $out
-      cat ${rootCA}/self/dep
-      echo ${rootCA}/self/dep > $out/dep
-    '';
-  };
-  transitivelyDependentCA = mkCADerivation {
-    name = "transitively-dependent";
-    buildCommand = ''
-      echo "building transitively-dependent"
-      cat ${dependentCA}/dep
-      echo ${dependentCA} > $out
-    '';
-  };
-  dependentNonCA = mkDerivation {
-    name = "dependent-non-ca";
-    buildCommand = ''
-      echo "Didn't cut-off"
-      echo "building dependent-non-ca"
-      mkdir -p $out
-      echo ${rootCA}/non-ca-hello > $out/dep
-    '';
-  };
-  dependentForBuildCA = mkCADerivation {
-    name = "dependent-for-build-ca";
-    buildCommand = ''
-      echo "Depends on rootCA for building only"
-      mkdir -p $out
-      echo ${rootCA}
-      touch $out
-    '';
-  };
-  dependentForBuildNonCA = mkDerivation {
-    name = "dependent-for-build-non-ca";
-    buildCommand = ''
-      echo "Depends on rootCA for building only"
-      mkdir -p $out
-      echo ${rootCA}
-      touch $out
-    '';
-  };
-  dependentFixedOutput = mkDerivation {
-    name = "dependent-fixed-output";
-    outputHashMode = "recursive";
-    outputHash = "sha512-7aJcmSuEuYP5tGKcmGY8bRr/lrCjJlOxP2mIUjO/vMQeg6gx/65IbzRWES8EKiPDOs9z+wF30lEfcwxM/cT4pw==";
-    buildCommand = ''
-      cat ${dependentCA}/dep
-      echo foo > $out
-    '';
-  };
-  runnable = mkCADerivation rec {
-    name = "runnable-thing";
-    buildCommand = ''
-      mkdir -p $out/bin
-      echo ${rootCA} # Just to make it depend on it
-      echo "#! ${shell}" > $out/bin/${name}
-      chmod +x $out/bin/${name}
-    '';
-  };
-}
diff --git a/tests/functional/ca/derivation-json.sh b/tests/functional/ca/derivation-json.sh
deleted file mode 100644
index 318a32ce0..000000000
--- a/tests/functional/ca/derivation-json.sh
+++ /dev/null
@@ -1,29 +0,0 @@
-source common.sh
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-
-drvPath=$(nix-instantiate ../simple.nix)
-
-nix derivation show $drvPath | jq .[] > $TEST_HOME/simple.json
-
-drvPath2=$(nix derivation add < $TEST_HOME/simple.json)
-
-[[ "$drvPath" = "$drvPath2" ]]
-
-# Content-addressed derivations can be renamed.
-jq '.name = "foo"' < $TEST_HOME/simple.json > $TEST_HOME/foo.json
-drvPath3=$(nix derivation add --dry-run < $TEST_HOME/foo.json)
-# With --dry-run nothing is actually written
-[[ ! -e "$drvPath3" ]]
-
-# But the JSON is rejected without the experimental feature
-expectStderr 1 nix derivation add < $TEST_HOME/foo.json --experimental-features nix-command | grepQuiet "experimental Lix feature 'ca-derivations' is disabled"
-
-# Without --dry-run it is actually written
-drvPath4=$(nix derivation add < $TEST_HOME/foo.json)
-[[ "$drvPath4" = "$drvPath3" ]]
-[[ -e "$drvPath3" ]]
-
-# The modified derivation read back as JSON matches
-nix derivation show $drvPath3 | jq .[] > $TEST_HOME/foo-read.json
-diff $TEST_HOME/foo.json $TEST_HOME/foo-read.json
diff --git a/tests/functional/ca/duplicate-realisation-in-closure.sh b/tests/functional/ca/duplicate-realisation-in-closure.sh
deleted file mode 100644
index da9cd8fb4..000000000
--- a/tests/functional/ca/duplicate-realisation-in-closure.sh
+++ /dev/null
@@ -1,26 +0,0 @@
-source ./common.sh
-
-requireDaemonNewerThan "2.4pre20210625"
-
-export REMOTE_STORE_DIR="$TEST_ROOT/remote_store"
-export REMOTE_STORE="file://$REMOTE_STORE_DIR"
-
-rm -rf $REMOTE_STORE_DIR
-clearStore
-
-# Build dep1 and push that to the binary cache.
-# This entails building (and pushing) current-time.
-nix copy --to "$REMOTE_STORE" -f nondeterministic.nix dep1
-clearStore
-sleep 2 # To make sure that `$(date)` will be different
-# Build dep2.
-# As we’ve cleared the cache, we’ll have to rebuild current-time. And because
-# the current time isn’t the same as before, this will yield a new (different)
-# realisation
-nix build -f nondeterministic.nix dep2 --no-link
-
-# Build something that depends both on dep1 and dep2.
-# If everything goes right, we should rebuild dep2 rather than fetch it from
-# the cache (because that would mean duplicating `current-time` in the closure),
-# and have `dep1 == dep2`.
-nix build --substituters "$REMOTE_STORE" -f nondeterministic.nix toplevel --no-require-sigs --no-link
diff --git a/tests/functional/ca/eval-store.sh b/tests/functional/ca/eval-store.sh
deleted file mode 100755
index 9cc499606..000000000
--- a/tests/functional/ca/eval-store.sh
+++ /dev/null
@@ -1,10 +0,0 @@
-#!/usr/bin/env bash
-
-# Ensure that garbage collection works properly with ca derivations
-
-source common.sh
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-
-cd ..
-source eval-store.sh
diff --git a/tests/functional/ca/flake.nix b/tests/functional/ca/flake.nix
deleted file mode 100644
index 332c92a67..000000000
--- a/tests/functional/ca/flake.nix
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  outputs = { self }: import ./content-addressed.nix {};
-}
diff --git a/tests/functional/ca/gc.sh b/tests/functional/ca/gc.sh
deleted file mode 100755
index e9b6c5ab5..000000000
--- a/tests/functional/ca/gc.sh
+++ /dev/null
@@ -1,10 +0,0 @@
-#!/usr/bin/env bash
-
-# Ensure that garbage collection works properly with ca derivations
-
-source common.sh
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-
-cd ..
-source gc.sh
diff --git a/tests/functional/ca/import-derivation.sh b/tests/functional/ca/import-derivation.sh
deleted file mode 100644
index bc72011f9..000000000
--- a/tests/functional/ca/import-derivation.sh
+++ /dev/null
@@ -1,5 +0,0 @@
-source common.sh
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-
-cd .. && source import-derivation.sh
diff --git a/tests/functional/ca/meson.build b/tests/functional/ca/meson.build
deleted file mode 100644
index f3f4a3b2b..000000000
--- a/tests/functional/ca/meson.build
+++ /dev/null
@@ -1,6 +0,0 @@
-# test_confdata set from tests/functional/meson.build
-configure_file(
-  input : 'config.nix.in',
-  output : 'config.nix',
-  configuration : test_confdata,
-)
diff --git a/tests/functional/ca/new-build-cmd.sh b/tests/functional/ca/new-build-cmd.sh
deleted file mode 100644
index 432d4d132..000000000
--- a/tests/functional/ca/new-build-cmd.sh
+++ /dev/null
@@ -1,5 +0,0 @@
-source common.sh
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-cd ..
-source ./build.sh
diff --git a/tests/functional/ca/nix-copy.sh b/tests/functional/ca/nix-copy.sh
deleted file mode 100755
index 7a8307a4e..000000000
--- a/tests/functional/ca/nix-copy.sh
+++ /dev/null
@@ -1,31 +0,0 @@
-#!/usr/bin/env bash
-
-source common.sh
-
-export REMOTE_STORE_DIR="$TEST_ROOT/remote_store"
-export REMOTE_STORE="file://$REMOTE_STORE_DIR"
-
-ensureCorrectlyCopied () {
-    attrPath="$1"
-    nix build --store "$REMOTE_STORE" --file ./content-addressed.nix "$attrPath"
-}
-
-testOneCopy () {
-    clearStore
-    rm -rf "$REMOTE_STORE_DIR"
-
-    attrPath="$1"
-    nix copy --to $REMOTE_STORE "$attrPath" --file ./content-addressed.nix
-
-    ensureCorrectlyCopied "$attrPath"
-
-    # Ensure that we can copy back what we put in the store
-    clearStore
-    nix copy --from $REMOTE_STORE \
-        --file ./content-addressed.nix "$attrPath" \
-        --no-check-sigs
-}
-
-for attrPath in rootCA dependentCA transitivelyDependentCA dependentNonCA dependentFixedOutput; do
-    testOneCopy "$attrPath"
-done
diff --git a/tests/functional/ca/nix-run.sh b/tests/functional/ca/nix-run.sh
deleted file mode 100755
index 5f46518e8..000000000
--- a/tests/functional/ca/nix-run.sh
+++ /dev/null
@@ -1,7 +0,0 @@
-#!/usr/bin/env bash
-
-source common.sh
-
-FLAKE_PATH=path:$PWD
-
-nix run --no-write-lock-file $FLAKE_PATH#runnable
diff --git a/tests/functional/ca/nix-shell.sh b/tests/functional/ca/nix-shell.sh
deleted file mode 100755
index a9b09069e..000000000
--- a/tests/functional/ca/nix-shell.sh
+++ /dev/null
@@ -1,7 +0,0 @@
-#!/usr/bin/env bash
-
-source common.sh
-
-CONTENT_ADDRESSED=true
-cd ../nix-shell
-source ./basic.sh
diff --git a/tests/functional/ca/nondeterministic.nix b/tests/functional/ca/nondeterministic.nix
deleted file mode 100644
index 642ec32ae..000000000
--- a/tests/functional/ca/nondeterministic.nix
+++ /dev/null
@@ -1,34 +0,0 @@
-with import ./config.nix;
-
-let mkCADerivation = args: mkDerivation ({
-    __contentAddressed = true;
-    outputHashMode = "recursive";
-    outputHashAlgo = "sha256";
-} // args);
-in
-
-rec {
-  currentTime = mkCADerivation {
-    name = "current-time";
-    buildCommand = ''
-      mkdir $out
-      echo $(date) > $out/current-time
-    '';
-  };
-  dep = seed: mkCADerivation {
-    name = "dep";
-    inherit seed;
-    buildCommand = ''
-      echo ${currentTime} > $out
-    '';
-  };
-  dep1 = dep 1;
-  dep2 = dep 2;
-  toplevel = mkCADerivation {
-    name = "toplevel";
-    buildCommand = ''
-      test ${dep1} == ${dep2}
-      touch $out
-    '';
-  };
-}
diff --git a/tests/functional/ca/post-hook.sh b/tests/functional/ca/post-hook.sh
deleted file mode 100755
index 3a90d2795..000000000
--- a/tests/functional/ca/post-hook.sh
+++ /dev/null
@@ -1,9 +0,0 @@
-#!/usr/bin/env bash
-
-source common.sh
-
-requireDaemonNewerThan "2.4pre20210626"
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-cd ..
-source ./post-hook.sh
diff --git a/tests/functional/ca/racy.nix b/tests/functional/ca/racy.nix
deleted file mode 100644
index 555a15484..000000000
--- a/tests/functional/ca/racy.nix
+++ /dev/null
@@ -1,15 +0,0 @@
-# A derivation that would certainly fail if several builders tried to
-# build it at once.
-
-
-with import ./config.nix;
-
-mkDerivation {
-  name = "simple";
-  buildCommand = ''
-    mkdir $out
-    echo bar >> $out/foo
-    sleep 3
-    [[ "$(cat $out/foo)" == bar ]]
-  '';
-}
diff --git a/tests/functional/ca/repl.sh b/tests/functional/ca/repl.sh
deleted file mode 100644
index 3808c7cb2..000000000
--- a/tests/functional/ca/repl.sh
+++ /dev/null
@@ -1,5 +0,0 @@
-source common.sh
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-
-cd .. && source repl.sh
diff --git a/tests/functional/ca/selfref-gc.sh b/tests/functional/ca/selfref-gc.sh
deleted file mode 100755
index 248778894..000000000
--- a/tests/functional/ca/selfref-gc.sh
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/usr/bin/env bash
-
-source common.sh
-
-requireDaemonNewerThan "2.4pre20210626"
-
-enableFeatures "ca-derivations nix-command flakes"
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-cd ..
-source ./selfref-gc.sh
diff --git a/tests/functional/ca/signatures.sh b/tests/functional/ca/signatures.sh
deleted file mode 100644
index eb18a4130..000000000
--- a/tests/functional/ca/signatures.sh
+++ /dev/null
@@ -1,36 +0,0 @@
-source common.sh
-
-clearStore
-clearCache
-
-nix-store --generate-binary-cache-key cache1.example.org $TEST_ROOT/sk1 $TEST_ROOT/pk1
-pk1=$(cat $TEST_ROOT/pk1)
-
-export REMOTE_STORE_DIR="$TEST_ROOT/remote_store"
-export REMOTE_STORE="file://$REMOTE_STORE_DIR"
-
-ensureCorrectlyCopied () {
-    attrPath="$1"
-    nix build --store "$REMOTE_STORE" --file ./content-addressed.nix "$attrPath"
-}
-
-testOneCopy () {
-    clearStore
-    rm -rf "$REMOTE_STORE_DIR"
-
-    attrPath="$1"
-    nix copy -vvvv --to $REMOTE_STORE "$attrPath" --file ./content-addressed.nix \
-        --secret-key-files "$TEST_ROOT/sk1" --show-trace
-
-    ensureCorrectlyCopied "$attrPath"
-
-    # Ensure that we can copy back what we put in the store
-    clearStore
-    nix copy --from $REMOTE_STORE \
-        --file ./content-addressed.nix "$attrPath" \
-        --trusted-public-keys $pk1
-}
-
-for attrPath in rootCA dependentCA transitivelyDependentCA dependentNonCA dependentFixedOutput; do
-    testOneCopy "$attrPath"
-done
diff --git a/tests/functional/ca/substitute.sh b/tests/functional/ca/substitute.sh
deleted file mode 100755
index ea981adc4..000000000
--- a/tests/functional/ca/substitute.sh
+++ /dev/null
@@ -1,71 +0,0 @@
-#!/usr/bin/env bash
-
-# Ensure that binary substitution works properly with ca derivations
-
-source common.sh
-
-needLocalStore "“--no-require-sigs” can’t be used with the daemon"
-
-rm -rf $TEST_ROOT/binary_cache
-
-export REMOTE_STORE_DIR=$TEST_ROOT/binary_cache
-export REMOTE_STORE=file://$REMOTE_STORE_DIR
-
-buildDrvs () {
-    nix build --file ./content-addressed.nix -L --no-link "$@"
-}
-
-# Populate the remote cache
-clearStore
-nix copy --to $REMOTE_STORE --file ./content-addressed.nix
-
-# Restart the build on an empty store, ensuring that we don't build
-clearStore
-buildDrvs --substitute --substituters $REMOTE_STORE --no-require-sigs -j0 transitivelyDependentCA
-# Check that the thing we’ve just substituted has its realisation stored
-nix realisation info --file ./content-addressed.nix transitivelyDependentCA
-# Check that its dependencies have it too
-nix realisation info --file ./content-addressed.nix dependentCA
-# nix realisation info --file ./content-addressed.nix rootCA --outputs out
-
-if isDaemonNewer "2.13"; then
-    pushToStore="../push-to-store.sh"
-else
-    pushToStore="../push-to-store-old.sh"
-fi
-
-# Same thing, but
-# 1. With non-ca derivations
-# 2. Erasing the realisations on the remote store
-#
-# Even in that case, realising the derivations should still produce the right
-# realisations on the local store
-#
-# Regression test for #4725
-clearStore
-nix build --file ../simple.nix -L --no-link --post-build-hook "$pushToStore"
-clearStore
-rm -r "$REMOTE_STORE_DIR/realisations"
-nix build --file ../simple.nix -L --no-link --substitute --substituters "$REMOTE_STORE" --no-require-sigs -j0
-# There's no easy way to check whether a realisation is present on the local
-# store − short of manually querying the db, but the build environment doesn't
-# have the sqlite binary − so we instead push things again, and check that the
-# realisations have correctly been pushed to the remote store
-nix copy --to "$REMOTE_STORE" --file ../simple.nix
-if [[ -z "$(ls "$REMOTE_STORE_DIR/realisations")" ]]; then
-    echo "Realisations not rebuilt"
-    exit 1
-fi
-
-# Test the local realisation disk cache
-buildDrvs --post-build-hook "$pushToStore"
-clearStore
-# Add the realisations of rootCA to the cachecache
-clearCacheCache
-export _NIX_FORCE_HTTP=1
-buildDrvs --substitute --substituters $REMOTE_STORE --no-require-sigs -j0
-# Try rebuilding, but remove the realisations from the remote cache to force
-# using the cachecache
-clearStore
-rm $REMOTE_STORE_DIR/realisations/*
-buildDrvs --substitute --substituters $REMOTE_STORE --no-require-sigs -j0
diff --git a/tests/functional/ca/why-depends.sh b/tests/functional/ca/why-depends.sh
deleted file mode 100644
index 0c079f63b..000000000
--- a/tests/functional/ca/why-depends.sh
+++ /dev/null
@@ -1,5 +0,0 @@
-source common.sh
-
-export NIX_TESTS_CA_BY_DEFAULT=1
-
-cd .. && source why-depends.sh
diff --git a/tests/functional/meson.build b/tests/functional/meson.build
index d989713d0..8dd142ccf 100644
--- a/tests/functional/meson.build
+++ b/tests/functional/meson.build
@@ -23,9 +23,7 @@ config_nix_in = configure_file(
   configuration : test_confdata,
 )
 
-# Just configures `ca/config.nix.in`. Done as a subdir() for the same reason as above.
-subdir('ca')
-# Just configures `nix-shell/config.nix.in`. Same as above.
+# Just configures `nix-shell/config.nix.in`. Done as a subdir() for the same reason as above.
 subdir('nix-shell')
 
 subdir('plugins')
@@ -34,24 +32,6 @@ subdir('test-libstoreconsumer')
 functional_tests_scripts = [
   'init.sh',
   'test-infra.sh',
-  'ca/build.sh',
-  'ca/build-cache.sh',
-  'ca/concurrent-builds.sh',
-  'ca/derivation-json.sh',
-  'ca/duplicate-realisation-in-closure.sh',
-  'ca/eval-store.sh',
-  'ca/gc.sh',
-  'ca/import-derivation.sh',
-  'ca/new-build-cmd.sh',
-  'ca/nix-copy.sh',
-  'ca/nix-run.sh',
-  'ca/nix-shell.sh',
-  'ca/post-hook.sh',
-  'ca/repl.sh',
-  'ca/selfref-gc.sh',
-  'ca/signatures.sh',
-  'ca/substitute.sh',
-  'ca/why-depends.sh',
   'flakes/flakes.sh',
   'flakes/develop.sh',
   'flakes/develop-r8854.sh',
@@ -121,7 +101,6 @@ functional_tests_scripts = [
   'dependencies.sh',
   'check-reqs.sh',
   'build-remote-content-addressed-fixed.sh',
-  'build-remote-content-addressed-floating.sh',
   'build-remote-trustless-should-pass-0.sh',
   'build-remote-trustless-should-pass-1.sh',
   'build-remote-trustless-should-pass-2.sh',
diff --git a/tests/functional/nix-profile.sh b/tests/functional/nix-profile.sh
index 13a73ead9..150650a55 100644
--- a/tests/functional/nix-profile.sh
+++ b/tests/functional/nix-profile.sh
@@ -3,7 +3,6 @@ source common.sh
 clearStore
 clearProfiles
 
-enableFeatures "ca-derivations"
 restartDaemon
 
 # Make a flake.
@@ -105,24 +104,10 @@ nix profile remove simple-1 2>&1 | grep 'removed 1 packages'
 nix profile wipe-history
 [[ $(nix profile history | grep Version | wc -l) -eq 1 ]]
 
-# Test upgrade to CA package.
-printf true > $flake1Dir/ca.nix
-printf 3.0 > $flake1Dir/version
-nix profile upgrade flake1
-nix profile history | grep "packages.$system.default: 1.0, 1.0-man -> 3.0, 3.0-man"
-
-# Test new install of CA package.
-nix profile remove flake1 2>&1 | grep 'removed 1 packages'
-printf 4.0 > $flake1Dir/version
-printf Utrecht > $flake1Dir/who
-nix profile install $flake1Dir
-[[ $($TEST_HOME/.nix-profile/bin/hello) = "Hello Utrecht" ]]
-[[ $(nix path-info --json $(realpath $TEST_HOME/.nix-profile/bin/hello) | jq -r .[].ca) =~ fixed:r:sha256: ]]
-
 # Override the outputs.
 nix profile remove simple flake1
 nix profile install "$flake1Dir^*"
-[[ $($TEST_HOME/.nix-profile/bin/hello) = "Hello Utrecht" ]]
+[[ $($TEST_HOME/.nix-profile/bin/hello) = "Hello NixOS" ]]
 [ -e $TEST_HOME/.nix-profile/share/man ]
 [ -e $TEST_HOME/.nix-profile/include ]
 
diff --git a/tests/functional/repl.sh b/tests/functional/repl.sh
index e205fc812..54acc4986 100644
--- a/tests/functional/repl.sh
+++ b/tests/functional/repl.sh
@@ -125,16 +125,6 @@ drvPath
 ' '".*-simple.drv"' \
 --file $testDir/simple.nix
 
-testReplResponse '
-drvPath
-' '".*-simple.drv"' \
---file $testDir/simple.nix --experimental-features 'ca-derivations'
-
-testReplResponse '
-drvPath
-' '".*-simple.drv"' \
---file $testDir/simple.nix --extra-experimental-features 'ca-derivations'
-
 mkdir -p flake && cat <<EOF > flake/flake.nix
 {
     outputs = { self }: {
diff --git a/tests/unit/libexpr/derived-path.cc b/tests/unit/libexpr/derived-path.cc
index 7257ba410..dfcce516e 100644
--- a/tests/unit/libexpr/derived-path.cc
+++ b/tests/unit/libexpr/derived-path.cc
@@ -46,7 +46,7 @@ RC_GTEST_FIXTURE_PROP(
      * to worry about race conditions if the tests run concurrently.
      */
     ExperimentalFeatureSettings mockXpSettings;
-    mockXpSettings.set("experimental-features", "ca-derivations");
+    mockXpSettings.experimentalFeatures.override(ExperimentalFeatures{} | Xp::CaDerivations);
 
     auto * v = evaluator.mem.allocValue();
     state.mkOutputString(*v, b, std::nullopt, mockXpSettings);
diff --git a/tests/unit/libstore/derivation.cc b/tests/unit/libstore/derivation.cc
index fca6b06c8..69fe7c484 100644
--- a/tests/unit/libstore/derivation.cc
+++ b/tests/unit/libstore/derivation.cc
@@ -1,6 +1,7 @@
 #include <gtest/gtest.h>
 
 #include "lix/libstore/derivations.hh"
+#include "lix/libutil/experimental-features.hh"
 #include "lix/libutil/json.hh"
 #include "lix/libutil/strings.hh"
 
@@ -29,7 +30,7 @@ class CaDerivationTest : public DerivationTest
 {
     void SetUp() override
     {
-        mockXpSettings.set("experimental-features", "ca-derivations");
+        mockXpSettings.experimentalFeatures.override(ExperimentalFeatures{} | Xp::CaDerivations);
     }
 };
 
diff --git a/tests/unit/libstore/downstream-placeholder.cc b/tests/unit/libstore/downstream-placeholder.cc
index d67932f35..069e259f5 100644
--- a/tests/unit/libstore/downstream-placeholder.cc
+++ b/tests/unit/libstore/downstream-placeholder.cc
@@ -10,7 +10,7 @@ TEST(DownstreamPlaceholder, unknownCaOutput) {
      * to worry about race conditions if the tests run concurrently.
      */
     ExperimentalFeatureSettings mockXpSettings;
-    mockXpSettings.set("experimental-features", "ca-derivations");
+    mockXpSettings.experimentalFeatures.override(ExperimentalFeatures{} | Xp::CaDerivations);
 
     ASSERT_EQ(
         DownstreamPlaceholder::unknownCaOutput(