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Firefox won't open web pages after Catalina upgrade

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  • Last reply by cor-el

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I upgraded to Catalina (Mac OS 10.15.6) from High Sierra and now Firefox 79.0 won't open most web pages--it just displays a blank window and a little dot dancing left & right in the tab. A few web pages (e.g., support.mozilla.org) work OK. I restarted Firefox in safe mode; rebooted the system; and searched System Preferences/Security & Privacy in vain for a request from Firefox but nothing helps. Suggestions?

Also, Catalina crashes and restarts about twice a day, so far always when I'm out of the room, but I don't know if Firefox has a hand in it.

--Tom

I upgraded to Catalina (Mac OS 10.15.6) from High Sierra and now Firefox 79.0 won't open most web pages--it just displays a blank window and a little dot dancing left & right in the tab. A few web pages (e.g., support.mozilla.org) work OK. I restarted Firefox in safe mode; rebooted the system; and searched System Preferences/Security & Privacy in vain for a request from Firefox but nothing helps. Suggestions? Also, Catalina crashes and restarts about twice a day, so far always when I'm out of the room, but I don't know if Firefox has a hand in it. --Tom

Chosen solution

Note that the System Details list shows you have multiple Flash plugins, one a very old Flash 10.0 version that you should remove.

  • Shockwave Flash 10.0 r45
  • Shockwave Flash 32.0 r0

You can find the location of a plugin on the about:plugins page and in the pluginreg.dat file in the Firefox profile folder.

You can check the version of the currently installed Flash plugin here:

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Chosen Solution

Note that the System Details list shows you have multiple Flash plugins, one a very old Flash 10.0 version that you should remove.

  • Shockwave Flash 10.0 r45
  • Shockwave Flash 32.0 r0

You can find the location of a plugin on the about:plugins page and in the pluginreg.dat file in the Firefox profile folder.

You can check the version of the currently installed Flash plugin here:

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Per your suggestion, I disabled the Flash plugins and all the add-ons, then restarted. The problem persisted, but I only tried it on one web site (wunderground.com; I should have tried a few more). Then I downloaded Firefox 79.0 (same version as the one I had) and reinstalled it. I tried again and the problem persists on wunderground.com. HOWEVER, I then tried other web sites and can't reproduce the problem anywhere else. Previously about 2/3 of the web sites I tried to visit would fail. So now I'm very puzzled but will continue and make note of any other web sites that fail.

Another question:

I didn't want to lose my bookmarks, so I went to the bookmarks window and made a backup. Then I looked in Library/Application Support/Firefox where I see a folder bookmarkbackups, dated today, with 15 recent files of ~250KB each called "bookmarks-2020-05-22_2672_8SE15v6edc+06-7fcvrWWg==.jsonlz4", etc.

When I reinstalled the Firefox app, all the bookmarks & Add-ons remained intact and restoring was unnecessary--can I always count on that?

In Library/... I also see a bunch of .html files called bookmarks-1, 2, 3, ... all dated 2006-08. Should I keep or delete those?

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Per your suggestion, I disabled the Flash plugins and all the add-ons, then restarted. The problem persisted, but I only tried it on one web site (wunderground.com; I should have tried a few more). Then I downloaded Firefox 79.0 (same version as the one I had) and reinstalled it. I tried again and the problem persists on wunderground.com. HOWEVER, I then tried other web sites and can't reproduce the problem anywhere else. Previously about 2/3 of the web sites I tried to visit would fail. So now I'm very puzzled but will continue and make note of any other web sites that fail.

Another question:

I didn't want to lose my bookmarks, so I went to the bookmarks window and made a backup. Then I looked in Library/Application Support/Firefox where I see a folder bookmarkbackups, dated today, with 15 recent files of ~250KB each called "bookmarks-2020-05-22_2672_8SE15v6edc+06-7fcvrWWg==.jsonlz4", etc.

When I reinstalled the Firefox app, all the bookmarks & Add-ons remained intact and restoring was unnecessary--can I always count on that?

In Library/... I also see a bunch of .html files called bookmarks-1, 2, 3, ... all dated 2006-08. Should I keep or delete those?

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Those HTML bookmarks-1, 2, 3 files are from 2006 created by a very old Firefox version, so they will have bookmarks from that date. Firefox creates numbered files when there is a problem with updating the main bookmarks.html file. You can open such a file in a Firefox tab if you want to check its content, but you can probably remove all these numbered bookmarks files and other numbered files if you have any.