From 061dbd627445d74feea2b2b63fbd47fe398e9da4 Mon Sep 17 00:00:00 2001
From: "microsoft-playwright-automation[bot]"
 <203992400+microsoft-playwright-automation[bot]@users.noreply.github.com>
Date: Wed, 2 Sep 2026 21:18:27 +0000
Subject: [PATCH] feat(firefox): roll to r1543

---
 browser_patches/firefox/juggler/NetworkObserver.js | 7 ++++++-
 packages/playwright-core/browsers.json             | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/browser_patches/firefox/juggler/NetworkObserver.js b/browser_patches/firefox/juggler/NetworkObserver.js
index ed048cc432fcc..2b4b3c5463f7c 100644
--- a/browser_patches/firefox/juggler/NetworkObserver.js
+++ b/browser_patches/firefox/juggler/NetworkObserver.js
@@ -909,7 +909,12 @@ class ResponseStorage {
     // Note: fulfilled request comes with decoded body right away.
     if ((request.httpChannel instanceof Ci.nsIEncodedChannel) && request.httpChannel.contentEncodings && !request.httpChannel.applyConversion && !request._fulfilled) {
       const encodingHeader = request.httpChannel.getResponseHeader("Content-Encoding");
-      encodings = encodingHeader.split(/\s*\t*,\s*\t*/);
+      // Firefox itself skips "identity" and empty encodings when applying content
+      // conversions, and there is no stream converter registered for them.
+      encodings = encodingHeader.split(/\s*\t*,\s*\t*/).filter(encoding => {
+        const normalized = encoding.trim().toLowerCase();
+        return normalized && normalized !== 'identity' && normalized !== 'x-identity';
+      });
     }
     this._responses.set(request.requestId, {
       body,
diff --git a/packages/playwright-core/browsers.json b/packages/playwright-core/browsers.json
index aeefe9c382a1a..5ed62af55d77c 100644
--- a/packages/playwright-core/browsers.json
+++ b/packages/playwright-core/browsers.json
@@ -17,7 +17,7 @@
     },
     {
       "name": "firefox",
-      "revision": "1542",
+      "revision": "1543",
       "installByDefault": true,
       "browserVersion": "155.0",
       "title": "Firefox"