diff --git a/.github/workflows/buildpack-integration-test.yml b/.github/workflows/buildpack-integration-test.yml
index 744e729a..fb820f9f 100644
--- a/.github/workflows/buildpack-integration-test.yml
+++ b/.github/workflows/buildpack-integration-test.yml
@@ -23,5 +23,5 @@ jobs:
       cloudevent-builder-source: 'test/conformance'
       cloudevent-builder-target: 'cloudevent_func'
       prerun: ${{format('test/conformance/prerun.sh {0} testdata/conformance/function', github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha )}}
-      builder-runtime: 'ruby30'
-      builder-runtime-version: '3.0'
+      builder-runtime: 'ruby31'
+      builder-runtime-version: '3.1'
diff --git a/.github/workflows/conformance.yml b/.github/workflows/conformance.yml
index b51da325..316be076 100644
--- a/.github/workflows/conformance.yml
+++ b/.github/workflows/conformance.yml
@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: ['3.0', '3.1', '3.2', '3.3']
+        ruby: ['3.1', '3.2', '3.3', '3.4']
     steps:
     - name: Harden Runner
       uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
@@ -71,4 +71,4 @@ jobs:
         useBuildpacks: false
         validateConcurrency: true
         cmd: "'bundle exec functions-framework-ruby --source test/conformance/app.rb --target concurrent_http_func --signature-type http'"
-    
+
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 88dff617..fbfee0c8 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -28,10 +28,10 @@ jobs:
 
     - name: Checkout repo
       uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-    - name: Install Ruby 3.0
+    - name: Install Ruby 3.1
       uses: ruby/setup-ruby@6c79f721fa26dd64559c2700086ac852c18e0756 # v1.225.0
       with:
-        ruby-version: "3.0"
+        ruby-version: "3.1"
         bundler-cache: true
     - name: Install toys
       run: gem install --no-document toys
diff --git a/.github/workflows/push-gh-pages.yml b/.github/workflows/push-gh-pages.yml
index 975e38db..1daf8a44 100644
--- a/.github/workflows/push-gh-pages.yml
+++ b/.github/workflows/push-gh-pages.yml
@@ -10,7 +10,7 @@ permissions: read-all
 jobs:
   push-gh-pages:
     env:
-      ruby_version: "3.0"
+      ruby_version: "3.1"
     runs-on: ubuntu-latest
 
     permissions:
diff --git a/.github/workflows/unit.yml b/.github/workflows/unit.yml
index b80d44bc..f59aced4 100644
--- a/.github/workflows/unit.yml
+++ b/.github/workflows/unit.yml
@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        ruby: ['3.0', '3.1', '3.2', '3.3']
+        ruby: ['3.1', '3.2', '3.3', '3.4']
         flags: ["--only --test-unit"]
         include:
           - os: ubuntu-latest
@@ -26,13 +26,13 @@ jobs:
             ruby: truffleruby
             flags: "--only --test-unit"
           - os: macos-latest
-            ruby: "3.0"
+            ruby: "3.1"
             flags: "--only --test-unit"
           - os: windows-latest
-            ruby: "3.0"
+            ruby: "3.2" # 3.1 fails similar to https://github.com/rubygems/rubygems/issues/4338
             flags: "--only --test-unit"
           - os: ubuntu-latest
-            ruby: "3.0"
+            ruby: "3.1"
             flags: "--only --test-yardoc --test-build --test-examples"
       fail-fast: false
     runs-on: ${{ matrix.os }}
diff --git a/Gemfile b/Gemfile
index 932edc0a..d0220dbe 100644
--- a/Gemfile
+++ b/Gemfile
@@ -16,6 +16,7 @@ source "https://rubygems.org"
 
 gemspec
 
+gem "base64"
 gem "google-style", "~> 1.30.1"
 gem "minitest", "~> 5.16"
 gem "minitest-focus", "~> 1.2"
diff --git a/test/test_server.rb b/test/test_server.rb
index 6f79f573..78eb8aee 100644
--- a/test/test_server.rb
+++ b/test/test_server.rb
@@ -203,7 +203,7 @@ def query_server_with_retry server
     end
 
     assert_equal "400", response.code
-    assert_equal "unexpected token at 'not json'", response.body
+    assert_match(/unexpected token/, response.body)
     assert_equal "text/plain; charset=utf-8", response["Content-Type"]
   end