diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index bf051bf3f..3eca8742f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -11,9 +11,10 @@ on:
 
 jobs:
   build:
-    name: build-${{ matrix.os }}-${{ matrix.ghc }}
-    runs-on: ${{ matrix.os }}
-
+    name: "Ubuntu: ${{ matrix.os }}, GHC: ${{ matrix.ghc }}"
+    env:
+      apps: "smp-server xftp-server ntf-server xftp"
+    runs-on: ubuntu-${{ matrix.os }}
     services:
       postgres:
         image: postgres:15
@@ -27,62 +28,49 @@ jobs:
         ports:
           # Maps tcp port 5432 on service container to the host
           - 5432:5432
-
     strategy:
       fail-fast: false
       matrix:
         include:
-          - os: ubuntu-20.04
-            platform_name: 20_04-x86-64
+          - os: 22.04
             ghc: "8.10.7"
-          - os: ubuntu-20.04
             platform_name: 20_04-x86-64
+          - os: 20.04
+            ghc: "9.6.3"
+            platform_name: 20_04-x86-64
+          - os: 22.04
             ghc: "9.6.3"
-          - os: ubuntu-22.04
             platform_name: 22_04-x86-64
+          - os: 24.04
             ghc: "9.6.3"
+            platform_name: 24_04-x86-64
     steps:
       - name: Clone project
         uses: actions/checkout@v3
 
-      - name: Setup Haskell
-        uses: haskell-actions/setup@v2
-        with:
-          ghc-version: ${{ matrix.ghc }}
-          cabal-version: "3.10.1.0"
-
-      - name: Cache dependencies
-        uses: actions/cache@v3
-        with:
-          path: |
-            ~/.cabal/store
-            dist-newstyle
-          key: ${{ matrix.os }}-${{ hashFiles('cabal.project', 'simplexmq.cabal') }}
-
-      - name: Build
+      - name: Prepare image
         shell: bash
-        run: cabal build --enable-tests
+        run: docker build -f Dockerfile.build --build-arg TAG=${{ matrix.os }} --build-arg GHC=${{ matrix.ghc }} -t local .
 
-      - name: Test
-        timeout-minutes: 40
+      - name: Start container
         shell: bash
-        run: cabal test --test-show-details=direct
-        env:
-          PGHOST: localhost
+        run: docker run -t -d --name builder local
 
-      - name: Prepare binaries
+      - name: Build binaries
+        shell: bash
+        run: docker exec -t -e apps="$apps" builder sh -c 'cabal build --enable-tests && mkdir /out && for i in $apps; do bin=$(find /project/dist-newstyle -name "$i" -type f -executable); strip "$bin"; chmod +x "$bin"; mv "$bin" /out/; done'
+
+      - name: Copy binaries from container and prepare them
         if: startsWith(github.ref, 'refs/tags/v')
         shell: bash
         run: |
-          mv $(cabal list-bin smp-server) smp-server-ubuntu-${{ matrix.platform_name}}
-          mv $(cabal list-bin ntf-server) ntf-server-ubuntu-${{ matrix.platform_name}}
-          mv $(cabal list-bin xftp-server) xftp-server-ubuntu-${{ matrix.platform_name}}
-          mv $(cabal list-bin xftp) xftp-ubuntu-${{ matrix.platform_name}}
+          docker cp builder:/out .
+          for i in $apps; do mv ./out/$i ./$i-ubuntu-${{ matrix.platform_name }}; done
 
       - name: Build changelog
         if: startsWith(github.ref, 'refs/tags/v')
         id: build_changelog
-        uses: mikepenz/release-changelog-builder-action@v1
+        uses: mikepenz/release-changelog-builder-action@v5
         with:
           configuration: .github/changelog_conf.json
           failOnError: true
@@ -93,7 +81,7 @@ jobs:
 
       - name: Create release
         if: startsWith(github.ref, 'refs/tags/v') && matrix.ghc != '8.10.7'
-        uses: softprops/action-gh-release@v1
+        uses: softprops/action-gh-release@v2
         with:
           body: |
             See full changelog [here](https://github.com/simplex-chat/simplexmq/blob/master/CHANGELOG.md).
@@ -103,10 +91,19 @@ jobs:
           prerelease: true
           files: |
             LICENSE
-            smp-server-ubuntu-${{ matrix.platform_name}}
-            ntf-server-ubuntu-${{ matrix.platform_name}}
-            xftp-server-ubuntu-${{ matrix.platform_name}}
-            xftp-ubuntu-${{ matrix.platform_name}}
+            smp-server-ubuntu-${{ matrix.platform_name }}
+            ntf-server-ubuntu-${{ matrix.platform_name }}
+            xftp-server-ubuntu-${{ matrix.platform_name }}
+            xftp-ubuntu-${{ matrix.platform_name }}
           fail_on_unmatched_files: true
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Test
+        shell: bash
+        env:
+          PGHOST: localhost
+        run: |
+          docker exec -t builder sh -c 'mv $(find /project/dist-newstyle -name "simplexmq-test" -type f -executable) /out/'
+          docker cp builder:/out/simplexmq-test .
+          ./simplexmq-test
diff --git a/Dockerfile.build b/Dockerfile.build
new file mode 100644
index 000000000..fb7678f44
--- /dev/null
+++ b/Dockerfile.build
@@ -0,0 +1,42 @@
+# syntax=docker/dockerfile:1.7.0-labs
+ARG TAG=24.04
+FROM ubuntu:${TAG} AS build
+
+### Build stage
+
+ARG GHC=9.6.3
+ARG CABAL=3.14.1.1
+
+# Install curl, git and and simplexmq dependencies
+RUN apt-get update && apt-get install -y curl git sqlite3 libsqlite3-dev build-essential libgmp3-dev zlib1g-dev llvm llvm-dev libnuma-dev libssl-dev
+
+# Specify bootstrap Haskell versions
+ENV BOOTSTRAP_HASKELL_GHC_VERSION=${GHC}
+ENV BOOTSTRAP_HASKELL_CABAL_VERSION=${CABAL}
+
+# Do not install Stack
+ENV BOOTSTRAP_HASKELL_INSTALL_NO_STACK=true
+ENV BOOTSTRAP_HASKELL_INSTALL_NO_STACK_HOOK=true
+
+# Install ghcup
+RUN curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | BOOTSTRAP_HASKELL_NONINTERACTIVE=1 sh
+
+# Adjust PATH
+ENV PATH="/root/.cabal/bin:/root/.ghcup/bin:$PATH"
+
+# Set both as default
+RUN ghcup set ghc "${GHC}" && \
+    ghcup set cabal "${CABAL}"
+
+# Copy only the source code
+COPY apps /project/apps/
+COPY cbits /project/cbits/
+COPY src /project/src/
+COPY tests /project/tests/
+
+COPY cabal.project Setup.hs simplexmq.cabal LICENSE /project
+
+WORKDIR /project
+
+# Compile app
+RUN cabal update
diff --git a/scripts/reproduce-builds.sh b/scripts/reproduce-builds.sh
new file mode 100755
index 000000000..eb35287ae
--- /dev/null
+++ b/scripts/reproduce-builds.sh
@@ -0,0 +1,30 @@
+#!/usr/bin/env sh
+set -eu
+
+tag="$1"
+
+git clone https://github.com/simplex-chat/simplexmq && cd simplexmq
+
+git checkout "$tag"
+
+for os in 20.04 22.04 24.04; do
+	mkdir -p out-${os}-github;
+
+	docker build -f Dockerfile.build --build-arg TAG=${os} -t repro-${os} .
+	docker run -t -d --name builder-${os} repro-${os}
+	
+	apps='smp-server xftp-server ntf-server xftp'
+	os_url="$(printf '%s' "$os" | tr '.' '_')"
+	
+	docker exec -t -e apps="$apps" builder-${os} sh -c 'cabal build && mkdir /out && for i in $apps; do bin=$(find /project/dist-newstyle -name "$i" -type f -executable); strip "$bin"; chmod +x "$bin"; mv "$bin" /out/; done'
+
+	docker cp builder-${os}:/out out-${os}
+	
+	for app in $apps; do
+		curl -L "https://github.com/simplex-chat/simplexmq/releases/download/${tag}/${app}-ubuntu-${os_url}-x86-64" -o out-${os}-github/${app}
+	done
+
+	docker stop builder-${os}
+	docker rm builder-${os} 
+	docker image rm repro-${os}
+done
diff --git a/simplexmq.cabal b/simplexmq.cabal
index d8a38e5ed..457394f72 100644
--- a/simplexmq.cabal
+++ b/simplexmq.cabal
@@ -1,7 +1,7 @@
 cabal-version: 1.12
 
 name:           simplexmq
-version:        6.3.0.6
+version:        6.3.0.8
 synopsis:       SimpleXMQ message broker
 description:    This package includes <./docs/Simplex-Messaging-Server.html server>,
                 <./docs/Simplex-Messaging-Client.html client> and
diff --git a/src/Simplex/Messaging/Protocol.hs b/src/Simplex/Messaging/Protocol.hs
index 679f077b7..122246868 100644
--- a/src/Simplex/Messaging/Protocol.hs
+++ b/src/Simplex/Messaging/Protocol.hs
@@ -1818,9 +1818,9 @@ tDecodeParseValidate THandleParams {sessionId, thVersion = v, implySessId} = \ca
 
 $(J.deriveJSON defaultJSON ''MsgFlags)
 
-$(J.deriveJSON (taggedObjectJSON id) ''CommandError)
+$(J.deriveJSON (sumTypeJSON id) ''CommandError)
 
-$(J.deriveJSON (taggedObjectJSON id) ''BrokerErrorType)
+$(J.deriveJSON (sumTypeJSON id) ''BrokerErrorType)
 
 $(J.deriveJSON defaultJSON ''BlockingInfo)
 
diff --git a/tests/ServerTests.hs b/tests/ServerTests.hs
index 5160070f0..c0232ec0f 100644
--- a/tests/ServerTests.hs
+++ b/tests/ServerTests.hs
@@ -871,7 +871,7 @@ testTiming =
         (C.AuthAlg C.SX25519, C.AuthAlg C.SX25519, 200) -- correct key type
       ]
     timeRepeat n = fmap fst . timeItT . forM_ (replicate n ()) . const
-    similarTime t1 t2 = abs (t2 / t1 - 1) < 0.25 -- normally the difference between "no queue" and "wrong key" is less than 5%
+    similarTime t1 t2 = abs (t2 / t1 - 1) < 0.30 -- normally the difference between "no queue" and "wrong key" is less than 5%
     testSameTiming :: forall c. Transport c => THandleSMP c 'TClient -> THandleSMP c 'TClient -> (C.AuthAlg, C.AuthAlg, Int) -> Expectation
     testSameTiming rh sh (C.AuthAlg goodKeyAlg, C.AuthAlg badKeyAlg, n) = do
       g <- C.newRandom