User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36

Steps to reproduce:

try to print or print preview - both just display a blank window.

Error console:
12:52:33.119 Uncaught ReferenceError: XPCOMUtils is not defined
<anonymous> chrome://global/content/printUtils.js:61
printUtils.js:61:1
<anonymous> chrome://global/content/printUtils.js:61
and
12:52:33.137 Uncaught TypeError: PrintUtils is undefined
PrintEngineCreateGlobals chrome://messenger/content/msgPrintEngine.js:30
OnLoadPrintEngine chrome://messenger/content/msgPrintEngine.js:21
onload chrome://messenger/content/msgPrintEngine.xhtml:1
msgPrintEngine.js:30:3

Not sure whether the update to 80.0b1 caused the problem but pretty sure that print was working on previous versions.
Also, not sure of any low level interdependencies between TB and firefox - have just deinstalled and reinstalled firefox (freeing up space from snap!!) after the update to 80.0b1 - could this be a cause?

Will try to revert to previous beta version and will post results.

thanks yes, we'll fix it
When you entered your summary, was Bugzilla not suggesting duplicates?
This has been reported several times so upon entering a new summary, existing duplicates should show...

FWICR bugzilla did not prompt about duplicates. I'm a long time TB user but 1st time I've had to file a bug so not familiar with bugzilla - sorry if it's a duplicate but very few bugs with "print" in the title, that's why I posted.
I'm on the beta path to try get back to using lightning connected to google calendar - and many other add-ons that got left by the wayside!
And please pass on to all - keep up the great work!

(In reply to clochrua from comment #3)

FWICR bugzilla did not prompt about duplicates. I'm a long time TB user but 1st time I've had to file a bug so not familiar with bugzilla - sorry if it's a duplicate but very few bugs with "print" in the title, that's why I posted.

Thanks!
You are right, seems that the duplicate checks are failing both guided and avanced bug entry form. Maybe because bugs have been duped to toolkit so duplicate checks might treat them as toolkit, not TB bugs.

I'm on the beta path to try get back to using lightning connected to google calendar - and many other add-ons that got left by the wayside!
And please pass on to all - keep up the great work!

Thank you! :-))