diff --git a/packages/playwright-core/src/server/dispatchers/localUtilsDispatcher.ts b/packages/playwright-core/src/server/dispatchers/localUtilsDispatcher.ts
index 82971d624a..b6f8fe80ac 100644
--- a/packages/playwright-core/src/server/dispatchers/localUtilsDispatcher.ts
+++ b/packages/playwright-core/src/server/dispatchers/localUtilsDispatcher.ts
@@ -348,8 +348,17 @@ class HarBackend {
           continue;
         if (method === 'POST' && postData && candidate.request.postData) {
           const buffer = await this._loadContent(candidate.request.postData);
-          if (!buffer.equals(postData))
-            continue;
+          if (!buffer.equals(postData)) {
+            const boundary = multipartBoundary(headers);
+            if (!boundary)
+              continue;
+            const candidataBoundary = multipartBoundary(candidate.request.headers);
+            if (!candidataBoundary)
+              continue;
+            // Try to match multipart/form-data ignroing boundary as it changes between requests.
+            if (postData.toString().replaceAll(boundary, '') !== buffer.toString().replaceAll(candidataBoundary, ''))
+              continue;
+          }
         }
         entries.push(candidate);
       }
@@ -437,3 +446,13 @@ export async function urlToWSEndpoint(progress: Progress|undefined, endpointURL:
   wsUrl.protocol = wsUrl.protocol === 'https:' ? 'wss:' : 'ws:';
   return wsUrl.toString();
 }
+
+function multipartBoundary(headers: HeadersArray) {
+  const contentType = headers.find(h => h.name.toLowerCase() === 'content-type');
+  if (!contentType?.value.includes('multipart/form-data'))
+    return undefined;
+  const boundary = contentType.value.match(/boundary=(\S+)/);
+  if (boundary)
+    return boundary[1];
+  return undefined;
+}
diff --git a/tests/library/browsercontext-har.spec.ts b/tests/library/browsercontext-har.spec.ts
index 6c31346e07..4a7834013a 100644
--- a/tests/library/browsercontext-har.spec.ts
+++ b/tests/library/browsercontext-har.spec.ts
@@ -412,6 +412,46 @@ it('should update har.zip for context', async ({ contextFactory, server }, testI
   await expect(page2.locator('body')).toHaveCSS('background-color', 'rgb(255, 192, 203)');
 });
 
+it('should ignore boundary when matching multipart/form-data body', {
+  annotation: { type: 'issue', description: 'https://github.com/microsoft/playwright/issues/31495' }
+}, async ({ contextFactory, server }, testInfo) => {
+  server.setRoute('/empty.html', (req, res) => {
+    res.setHeader('Content-Type', 'text/html');
+    res.end(`
+      <form id="form" action="form.html" enctype="multipart/form-data" method="POST">
+      <input id="file" type="file" multiple />
+      <button type="submit">Upload</button>
+      </form>`);
+  });
+  server.setRoute('/form.html', (req, res) => {
+    res.setHeader('Content-Type', 'text/html');
+    res.end('<div>done</div>');
+  });
+
+  const harPath = testInfo.outputPath('har.zip');
+  const context1 = await contextFactory();
+  await context1.routeFromHAR(harPath, { update: true });
+  const page1 = await context1.newPage();
+  await page1.goto(server.PREFIX + '/empty.html');
+  const reqPromise = server.waitForRequest('/form.html');
+  await page1.locator('button').click();
+  await expect(page1.locator('div')).toHaveText('done');
+  const req = await reqPromise;
+  expect((await req.postBody).toString()).toContain('---');
+  await context1.close();
+
+  const context2 = await contextFactory();
+  await context2.routeFromHAR(harPath, { notFound: 'abort' });
+  const page2 = await context2.newPage();
+  await page2.goto(server.PREFIX + '/empty.html');
+  const requestPromise = page2.waitForRequest(/.*form.html/);
+  await page2.locator('button').click();
+  const request = await requestPromise;
+  expect.soft(await request.response()).toBeTruthy();
+  expect(request.failure()).toBe(null);
+  await expect(page2.locator('div')).toHaveText('done');
+});
+
 it('should update har.zip for page', async ({ contextFactory, server }, testInfo) => {
   const harPath = testInfo.outputPath('har.zip');
   const context1 = await contextFactory();
@@ -428,7 +468,6 @@ it('should update har.zip for page', async ({ contextFactory, server }, testInfo
   await expect(page2.locator('body')).toHaveCSS('background-color', 'rgb(255, 192, 203)');
 });
 
-
 it('should update har.zip for page with different options', async ({ contextFactory, server }, testInfo) => {
   const harPath = testInfo.outputPath('har.zip');
   const context1 = await contextFactory();