From 20646fa1f9b4016129573e01c252ea8b8c28de00 Mon Sep 17 00:00:00 2001
From: Devin Binnie <52460000+devinbinnie@users.noreply.github.com>
Date: Fri, 8 May 2026 08:55:36 -0400
Subject: [PATCH] [MM-68690] Null check on missing headers when loading
 resources (#3812)

(cherry picked from commit 9538d4d18863a9aae47181911c7c2f5b1f372a5b)
---
 src/main/downloadsManager.test.js | 14 ++++++++++++++
 src/main/downloadsManager.ts      |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/main/downloadsManager.test.js b/src/main/downloadsManager.test.js
index 4cb5730748c..3d3b80400ac 100644
--- a/src/main/downloadsManager.test.js
+++ b/src/main/downloadsManager.test.js
@@ -180,6 +180,20 @@ describe('main/downloadsManager', () => {
         expect(dl.fileSizes.get('file.txt')).toBe('4242');
     });
 
+    it('MM-68690 - should not throw when content-disposition header is missing', () => {
+        const dl = new DownloadsManager({});
+        const details = {
+            responseHeaders: {
+                'content-encoding': ['gzip'],
+                'x-uncompressed-content-length': ['4242'],
+            },
+        };
+        const cb = jest.fn();
+        expect(() => dl.webRequestOnHeadersReceivedHandler(details, cb)).not.toThrow();
+        expect(cb).toHaveBeenCalledWith({});
+        expect(dl.fileSizes.size).toBe(0);
+    });
+
     it('should clear the downloads list', () => {
         const dl = new DownloadsManager(JSON.stringify(downloadsJson));
         dl.clearDownloadsDropDown();
diff --git a/src/main/downloadsManager.ts b/src/main/downloadsManager.ts
index abdb14f983b..6a1b2a65c92 100644
--- a/src/main/downloadsManager.ts
+++ b/src/main/downloadsManager.ts
@@ -150,7 +150,7 @@ export class DownloadsManager extends JsonFileManager<DownloadedItems> {
     webRequestOnHeadersReceivedHandler = (details: Electron.OnHeadersReceivedListenerDetails, cb: (headersReceivedResponse: Electron.HeadersReceivedResponse) => void) => {
         const headers = details.responseHeaders ?? {};
 
-        if (headers?.['content-encoding']?.includes('gzip') && headers?.['x-uncompressed-content-length'] && headers?.['content-disposition'].join(';')?.includes('filename=')) {
+        if (headers?.['content-encoding']?.includes('gzip') && headers?.['x-uncompressed-content-length'] && headers?.['content-disposition']?.join?.(';')?.includes('filename=')) {
             const filename = readFilenameFromContentDispositionHeader(headers['content-disposition']);
             const fileSize = headers['x-uncompressed-content-length']?.[0] || '0';
             if (filename && (!this.fileSizes.has(filename) || this.fileSizes.get(filename)?.toString() !== fileSize)) {