1512376 - Images from custom fonts (such as google calendar icons) shown as squares with four letters after leaving Firefox open for a while

Status: RESOLVED INCOMPLETE

(Firefox :: Untriaged, defect)

Description

[Ioannis Chronakis]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0

Steps to reproduce:

Firefox running for days without any problems. Typical setup is two windows. Each FF window is in a separate windows workspace/desktop and has 3-4 pinned tabs (gmail, google calendar and one or two google drive documents) and 10-20 normal tabs.

Without any recognisable usage pattern, at some point after a day or two or maybe more, when switching back to a tab, I can see the problem with the icons happening. I have seen this with google calendar icons and also once I had a complaint from a google document about fonts missing.



Actual results:

When switching to a tab that uses custom font based icons such as google calendar or linkedin, the images are replaced with squares with a 4 letter/digit code inside. In addition, google documents open for a while, display some times a message "Font can't be loaded". The problem appears when I switch to a tab, not the currently shown tab.

Reloading the page solves the problem and it may take days to happen again. Though in one instance, linked in icons refuse to show even after a reload.


Expected results:

Icons to be shown normally

Comment 1

[Daniel Bodea [:danibodea]]

I can't do any more than assume some causes of your issue.

Please restore the default font settings using the following instructions:
1. Go to the Windows 10 search field on the taskbar, and type Control Panel. Click on the Control Panel link under the search results, to open it. With the Control Panel open, go to Appearance and Personalization, and then Change Font Settings under Fonts.
2. Under Font Settings, click the Restore default font settings button. Windows 10 will then begin restoring the default fonts. Windows can also hide fonts that are not designed for your input language settings. To do this, select the Hide fonts based on language settings checkbox before clicking on the Restore default fonts button.

After this is done, please try to reproduce your issue again (considering that it's an issue that only rarely reproduces, you should probably wait for a few days and try to reproduce it intentionally in this time). If it stops reproducing, then we MAY have fixed the problem from outside the browser. If it still reproduces, then we should probably address the issue some other way. 

Please comment here any new test results. 
Thank you for your contribution!

P.S. If the issue reproduces, please also use the "print screen" option to show us how the icons become displayed incorrectly.

Comment 2

[Daniel Bodea [:danibodea]]

Based on the lack of information from the reporter this bug will have the Status: Resolved as incomplete.
If you want to add more info that can help to understand this bug please reopen it.