Affected versions

• 82.0a1 (BuildId:20200831091558)
• 81.0b4 (BuildId:20200829200810)

Affected platforms

• Windows 10 64bit
• Ubuntu 20.04 64bit
• macOS 10.14

Steps to reproduce

1. Launch Firefox.
2. Access the following link.
3. Select the Save to PDF printer destination (for me it displays that it will print 45 pages).
4. Select a page range from 44 to 45.
5. Change the destination to the actual physical printer (for me it display that it will print 25 pages).

Expected result

• The range is invalidated and once the user changes the page range to a valid one the print preview gets successfully updated/loaded.

Actual result

• The page range persists and it will be invalid but the print preview is stuck at the “Preparing Preview” state. It seems that changing the destination or the page range (to a valid one) still doesn’t exist the “Preparing Preview” state.

Regression Window

• I will search for a regression asap.

Additional Information

• For further information regarding this issue please observe the attached screencast.
• It seems that changing from the custom range field to all (if an invalid range was entered) locks the options (as seen inside the screencast). This seems to be a different issue (I'm going to log a separate issue for this in a few minutes).
• [Suggested Severity] S2

Comment on attachment 9173228 [details]
Bug 1662136 - Use DeferredTask to queue print preview updates r?emalysz

Beta/Release Uplift Approval Request

• User impact if declined: Print previews can get stuck in loading state when changing print range
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: No
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: See comment 0
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Moves from some custom promise queueing code to an already existing implementation that clearly works better :)
• String changes made/needed: No

https://hg.mozilla.org/mozilla-central/rev/076c6ff96476

This issue is verified fixed using Firefox 82.0a1 (BuildId:20200903094553) on Windows 10 64bit, macOS 10.14 & Ubuntu 18.04 64bit.

Leaving a ni? on myself and the qe-verify+ flag until this gets verified in beta as well.

Comment on attachment 9173228 [details]
Bug 1662136 - Use DeferredTask to queue print preview updates r?emalysz

Approved for 81.0b6.

https://hg.mozilla.org/releases/mozilla-beta/rev/9951b2b77c41

This issue is verified fixed using Firefox 81.0b7 (BuildId:20200906164749) on windows 10 64bit, macOS 10.14 & Ubuntu 18.04 64bit.