Mozilla releases Firefox 138.0.1 to fix Outlook bug & more

Mozilla has rolled out Firefox 138.0.1, a minor update addressing issues in the recently released Firefox 138. The Firefox 138.0.1, available as of May 1, 2025, fixes two bugs, of which one is related to Outlook. 

Mozilla details Outlook bugs in Firefox 138 and releases 138.0.1 as a fix

Many users have complained about seeing a blank page instead of the Home or New Tab pages. On top of that, users have reported another issue that has caused Outlook on the web to add UTF-8 to the beginning of the attachment file when saving.

In the changelog for Firefox 138.0.1, Mozilla noted:

Version 138.0.1, first offered to Release channel users on May 1, 2025

• Fixed an issue which caused a blank page to be shown for Home and New Tab pages for some users. (Bug 1963537)
• Added a workaround for a bug in outlook.office.com/outlook.live.com where attachment filenames are incorrectly prefixed with UTF-8 when saved. (Bug 1961710)

Also read: Mozilla Firefox 139 Beta improves PNG support, HTTP/3 performance & more

The latest version is available starting today

If you are downloading Firefox for the first time, download the 138.0.1 version from the official website. For those who have Firefox already installed, the update will be automatically pushed. If you want to do it manually, navigate to Menu > Help > About Firefox.

Earlier this week, Mozilla released the version 138 of Firefox, with profile manager feature, improved address bar, and tab groups. If you haven’t caught up, you can check everything here.