[Linux/Kubuntu] .docx files downloaded/re-uploaded from Google Drive are corrupted by Brave if saved with .docx extension

[BUG] .docx file corruption on download/re-upload from Google Drive on Kubuntu when saving with .docx extension in Brave.

Hello Brave Community,

I’m encountering a peculiar issue with Brave browser on Kubuntu when handling .docx files from Google Drive. This issue started after a recent Brave reinstallation.

Problem Description:
When I download a .docx file from Google Drive to my Kubuntu system using Brave, and then re-upload that same downloaded file back to Google Drive, the re-uploaded file becomes corrupted and cannot be opened by Google Docs (it prompts to open with third-party apps, or shows an error). This only happens if I save the file with the .docx extension during the download process.

Crucial Observation (and Workaround):
If I perform the exact same download process, but remove the .docx extension from the filename when saving it on Kubuntu (e.g., saving “document.docx” as “document”), then when I re-upload this extension-less file to Google Drive, Google Docs is able to open it normally. Kubuntu might show this extension-less file as “unidentified” locally, but Google Drive correctly recognizes its internal .docx format.

Comparison with other browsers:
I have tested this same workflow (downloading the .docx file and then re-uploading it to Google Drive) using Firefox on Kubuntu, and the issue DOES NOT occur. Files downloaded with the .docx extension in Firefox, and then re-uploaded, open perfectly fine in Google Docs. This strongly suggests the problem is specific to Brave on Linux.

Steps to Reproduce:

  1. Create a new .docx file on a Windows machine (using MS Word) or use any existing, known-good .docx file.

  2. Upload this .docx file to your Google Drive account.

  3. On Kubuntu, open Brave browser and navigate to Google Drive.

  4. Locate the .docx file uploaded in step 2.

  5. Attempt 1 (Problematic): Download the .docx file. In the Brave save dialog, ensure the file is saved with the .docx extension (e.g., my_document.docx).

  6. Upload this newly downloaded my_document.docx from Kubuntu back to Google Drive (you can rename it, e.g., my_document_uploaded_problem.docx).

  7. Try to open my_document_uploaded_problem.docx in Google Docs. Expected: It should open. Actual: It fails to open, offering third-party apps instead.

  8. Attempt 2 (Working Workaround): Repeat step 5, but this time, in the Brave save dialog, remove the .docx extension from the filename (e.g., save as my_document_no_ext).

  9. Upload this my_document_no_ext from Kubuntu back to Google Drive (e.g., my_document_uploaded_ok.docx).

  10. Try to open my_document_uploaded_ok.docx in Google Docs. Expected: It should open. Actual: It opens correctly.

Expected Behavior:
A .docx file downloaded with its correct extension from Google Drive should be able to be re-uploaded and opened correctly by Google Docs, just like it does when using Firefox or performing the download/re-upload on Windows.

Current Behavior:
Brave on Kubuntu seems to subtly corrupt .docx files during the download/save process if the .docx extension is present in the filename, rendering them unreadable by Google Docs upon re-upload.

My System Information:

  • Brave Version: 1.80.120 Chromium: 138.0.7204.101 (Official Build) (64-bit)
  • Operating System: 22.04 LTS
  • Linux Kernel: 6.11.0-29-generic
  • KDE Plasma Version: 5.27.12

Thank you for your assistance.