Affected versions

• 76.0b5, 77.0a1 (2020-04-15)

Affected platforms

• macOS 10.15.3;

Steps to reproduce

1. Launch Firefox, open any video ex: this one
2. Right click for the context menu;
3. Click on PIP to enable it;
4. Right click on the video for the context menu again;
5. Click on the Fullscreen option

Expected result

• fullscreen triggered;

Actual result

• fullscreen not triggered;

Regression range

• will check and provide one asap;
• Last good revision: 2019-10-25
• First bad revision: 2019-10-26
• Pushlog: URL

Additional notes

• on Ubuntu 18.04/Windows 10 it seems to work ok and goes full-screen mode;
• at some point the fullscreen gets triggered as well;
• error code displayed in console:
  [Exception... "Component returned failure code: 0x80070057 (NS_ERROR_ILLEGAL_VALUE) [nsIDOMWindowUtils.addSheet]" nsresult: "0x80070057 (NS_ERROR_ILLEGAL_VALUE)" location: "JS frame :: resource://gre/modules/ExtensionCommon.jsm :: runSafeSyncWithoutClone :: line 75" data: no]

Not a regression, updated section in the initial report.
Visible & reproducible with the introduction of the pip button/option.

Because this bug's Severity has not been changed from the default since it was filed, and it's Priority is P3 (Backlog,) indicating it has been triaged, the bug's Severity is being updated to S3 (normal.)

Is this a duplicate of bug #1534986?

Hi Cristian!

Are you still experiencing this issue? I'm not able to reproduce on macOS 11.6 - the full screen is successfully triggered for me after step 5.

Forwarding towards the QA team.

I can confirm that this issue is reproducible in Nightly v77.0a1 on Mac OS 11.6.0 and Windows 10, but it no longer reproduces in the latest Nightly v100.0a1. Based on the above, I will close this as worksforme.