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Application Handler Broken

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After opening a large number of tabs in rapid succession the application handler for Firefox no longer launches applications and either displays:

Firefox doesn’t know how to open this address, because one of the following protocols ([Whatever the protocol is]) isn’t associated with any program or is not allowed in this context.

Or simply does nothing

This occurs in safe mode and after a refresh. Other browsers (Chrome, Edge and Waterfox tested in this instance) but not Firefox previously I have got this working with a full uninstall and reinstall but it usually happens again after a few days

After opening a large number of tabs in rapid succession the application handler for Firefox no longer launches applications and either displays: Firefox doesn’t know how to open this address, because one of the following protocols ([Whatever the protocol is]) isn’t associated with any program or is not allowed in this context. Or simply does nothing This occurs in safe mode and after a refresh. Other browsers (Chrome, Edge and Waterfox tested in this instance) but not Firefox previously I have got this working with a full uninstall and reinstall but it usually happens again after a few days

All Replies (10)

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Hi Tyson C Rasanen , See if this article can help:

Firefox repeatedly opens empty tabs or windows after you click on a link

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Hey Robert,

In order of the solutions presented there:

  • I can say that all handles I CAN test don't work. So far I've texted NXM (Nexus's Vortex Mod Manager), Screenconnect-[GUID] (Screenconnect's native handle) and a generic mailto without success
  • I did try resetting handlers before posting. Sorry! Forgot to mention :)
  • I can say the PC has no malware per the scanners I have installed (Though given it works with other browsers I doubt you intended that one to be necessarily relevant anyways)
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While you're waiting for a response to your texts, have you checked your Windows file type associations?

Go to - Windows Settings -> Apps -> Default Apps (on the left) listed below the Reset button, you will see

  • Choose Default Apps By File Type
  • Choose Default Apps By Protocol
  • Set Defaults By App

Select *Choose Default Apps By File Type (it may take a minute for the list to load) find the file type and click on the line to the right of it to select an app.

Also check the others, if appropriate.

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Nothing out of the ordinary there. Like I stated earlier it DOES work on other browsers :)!

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There was a similar issue with a protocol not opening -

Check @jscher2000's response in this thread:

Firefox no longer able to open https://support.mozilla.org/en-US/questions/1274684

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Blasts, the about:config fix didn't work either

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Maybe you need to go on vacation like that user did :)

I'm about out of ideas but, I'll keep looking. Maybe someone else knows another trick or two.

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I'm not sure that it's appropriate here but, it looks interesting:

The Nexus Forums Manual Download (nxm protocol) https://forums.nexusmods.com/index.php?/topic/468427-manual-download-nxm-protocol/

The link in that thread for the ModManager is dead. I found it here: https://www.nexusmods.com/about/vortex/

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And maybe review the ScreenConnect Integration at:

Syncro Help Center https://help.syncromsp.com/hc/en-us/articles/360008240354-ScreenConnect-Integration#troubleshooting

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Looked through both of those, neither have helped in the past typically (Which would make sense given that other browsers still can access everything fine including a fork of Firefox)