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Testcomplete suddenly no longer recognizes Firefox

Occasional Contributor

Testcomplete suddenly no longer recognizes Firefox

Hello everybody,

I was executing my testcase today and it would not work, getting the error message that >The object "Sys.Browser("firefox")" does not exist.<

Yesterday, everything worked fine.

How do I fix this?

Esteemed Contributor

Verify a couple of things:


1) Firefox IS actually running and present in the Task manager in Windows

2) Firefox has not been updated recently.


My guess is #2 happened.  I looked online and see that Firefox 72 was JUST released yesterday.  Currently, TestComplete only has patches available through Firefox 71 so, if you are running 72, it's probably not being recognized.   You will need to roll back the Firefox version until Smartbear makes a patch available.


Best practice is to turn off automatic updates for browsers so that you have control of your environment.

Robert Martin
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Why automate?  I do automated testing because there's only so much a human being can do and remain healthy.  Sleep is a requirement.  So, while people sleep, automation that I create does what I've described above in order to make sure that nothing gets past the final defense of the testing group.
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Mysterious Gremlin Master
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Here you can already download Firefox 72 - even though it is not possible to update automatically in TestComplete

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