diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5960c672..0538be7d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -103,23 +103,26 @@ jobs:
           MOCHA_WEBDRIVER_SKIP_CLEANUP=1 MOCHA_WEBDRIVER_HEADLESS=1 yarn run test:nbrowser --parallel --jobs 3
         env:
           TESTS: ${{ matrix.tests }}
-          MOCHA_WEBDRIVER_LOGDIR: ${{ runner.temp }}/mocha-webdriver-logs
+          MOCHA_WEBDRIVER_LOGDIR: ${{ runner.temp }}/test-logs/webdriver
+          TESTDIR: ${{ runner.temp }}/test-logs
 
-      - name: Prepare a safe artifact name
+      - name: Prepare for saving artifact
         if: failure()
         run: |
           ARTIFACT_NAME=logs-$(echo $TESTS | sed 's/[^-a-zA-Z0-9]/_/g')
           echo "Artifact name is '$ARTIFACT_NAME'"
           echo "ARTIFACT_NAME=$ARTIFACT_NAME" >> $GITHUB_ENV
+          find $TESTDIR -iname "*.socket" -exec rm {} \;
         env:
           TESTS: ${{ matrix.tests }}
+          TESTDIR: ${{ runner.temp }}/test-logs
 
       - name: Save artifacts on failure
         if: failure()
         uses: actions/upload-artifact@v3
         with:
           name: ${{ env.ARTIFACT_NAME }}
-          path: ${{ runner.temp }}/mocha-webdriver-logs  # only exists for webdriver tests
+          path: ${{ runner.temp }}/test-logs  # only exists for webdriver tests
 
     services:
       # https://github.com/bitnami/bitnami-docker-minio/issues/16
diff --git a/buildtools/webpack.config.js b/buildtools/webpack.config.js
index 9e35f6a7..c66b1413 100644
--- a/buildtools/webpack.config.js
+++ b/buildtools/webpack.config.js
@@ -1,3 +1,4 @@
+const fs = require('fs');
 const MomentLocalesPlugin = require('moment-locales-webpack-plugin');
 const { ProvidePlugin } = require('webpack');
 const path = require('path');
@@ -15,7 +16,11 @@ module.exports = {
     account: "app/client/accountMain",
     billing: "app/client/billingMain",
     activation: "app/client/activationMain",
-    test: "test/client-harness/client",
+    // Include client test harness if it is present (it won't be in
+    // docker image).
+    ...(fs.existsSync("test/client-harness/client.js") ? {
+      test: "test/client-harness/client",
+    } : {}),
   },
   output: {
     filename: "[name].bundle.js",
diff --git a/test/fixtures/sites/config/page.js b/test/fixtures/sites/config/page.js
index 37bcc366..3340f201 100644
--- a/test/fixtures/sites/config/page.js
+++ b/test/fixtures/sites/config/page.js
@@ -4,27 +4,29 @@
 const urlParams = new URLSearchParams(window.location.search);
 const ready = urlParams.get('ready') ? JSON.parse(urlParams.get('ready')) : undefined;
 
-if (ready && ready.onEditOptions) {
-  ready.onEditOptions = () => {
-    document.getElementById('configure').innerHTML = 'called';
-  };
-}
+function setup() {
+  if (ready && ready.onEditOptions) {
+    ready.onEditOptions = () => {
+      document.getElementById('configure').innerHTML = 'called';
+    };
+  }
 
-grist.ready(ready);
+  grist.ready(ready);
 
-grist.onOptions(data => {
-  document.getElementById('onOptions').innerHTML = JSON.stringify(data);
-});
+  grist.onOptions(data => {
+    document.getElementById('onOptions').innerHTML = JSON.stringify(data);
+  });
 
-grist.onRecord((data, mappings) => {
-  document.getElementById('onRecord').innerHTML = JSON.stringify(data);
-  document.getElementById('onRecordMappings').innerHTML = JSON.stringify(mappings);
-});
+  grist.onRecord((data, mappings) => {
+    document.getElementById('onRecord').innerHTML = JSON.stringify(data);
+    document.getElementById('onRecordMappings').innerHTML = JSON.stringify(mappings);
+  });
 
-grist.onRecords((data, mappings) => {
-  document.getElementById('onRecords').innerHTML = JSON.stringify(data);
-  document.getElementById('onRecordsMappings').innerHTML = JSON.stringify(mappings);
-});
+  grist.onRecords((data, mappings) => {
+    document.getElementById('onRecords').innerHTML = JSON.stringify(data);
+    document.getElementById('onRecordsMappings').innerHTML = JSON.stringify(mappings);
+  });
+}
 
 async function run(handler) {
   try {
@@ -66,6 +68,7 @@ async function configure() {
 }
 
 window.onload = () => {
+  setup();
   document.getElementById('ready').innerText = 'ready';
   document.getElementById('access').innerHTML = urlParams.get('access');
   document.getElementById('readonly').innerHTML = urlParams.get('readonly');
diff --git a/test/nbrowser/Localization.ts b/test/nbrowser/Localization.ts
index 43da5800..b5fb4d40 100644
--- a/test/nbrowser/Localization.ts
+++ b/test/nbrowser/Localization.ts
@@ -116,8 +116,7 @@ describe("Localization", function() {
       // But only uz code is preloaded.
       notPresent(uzResponse, "uz-UZ");
 
-      // For Portuguese we have only en.
-      notPresent(ptResponse, "pt", "pt-PR", "uz", "en-US");
+      notPresent(ptResponse, "pt-PR", "uz", "en-US");
     });
 
     it("loads correct languages from file system", async function() {
diff --git a/test/nbrowser/testServer.ts b/test/nbrowser/testServer.ts
index 8bcce502..f69c1d56 100644
--- a/test/nbrowser/testServer.ts
+++ b/test/nbrowser/testServer.ts
@@ -65,14 +65,14 @@ export class TestServerMerged extends EventEmitter implements IMochaServer {
       await this.stop();
     }
     this._starts++;
+    const workerIdText = process.env.MOCHA_WORKER_ID || '0';
     if (reset) {
       if (process.env.TESTDIR) {
-        this.testDir = process.env.TESTDIR;
+        this.testDir = path.join(process.env.TESTDIR, workerIdText);
       } else {
-        const workerId = process.env.MOCHA_WORKER_ID || '0';
         // Create a testDir of the form grist_test_{USER}_{SERVER_NAME}_{WORKER_ID}, removing any previous one.
         const username = process.env.USER || "nobody";
-        this.testDir = path.join(tmpdir(), `grist_test_${username}_${this._name}_${workerId}`);
+        this.testDir = path.join(tmpdir(), `grist_test_${username}_${this._name}_${workerIdText}`);
         await fse.remove(this.testDir);
       }
     }
@@ -99,7 +99,7 @@ export class TestServerMerged extends EventEmitter implements IMochaServer {
     // logging. Server code uses a global logger, so it's hard to separate out (especially so if
     // we ever run different servers for different tests).
     const serverLog = process.env.VERBOSE ? 'inherit' : nodeLogFd;
-    const workerId = parseInt(process.env.MOCHA_WORKER_ID || '0', 10);
+    const workerId = parseInt(workerIdText, 10);
     const corePort = String(8295 + workerId * 2);
     const untrustedPort = String(8295 + workerId * 2 + 1);
     const env: Record<string, string> = {