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Thunderbird incompatible with Mac OS 10.15.5?

After updating Mac OS 10.15.5 I find that Thunderbird 68.8.1 will freeze before fully loading. Is Thunderbird incompatible with the updated Mac OS 10.15.5?

I simply cannot use Thunderbird since the fix to Mac OS 10.15.5 I installed yesterday. June 2, 2020.

After updating Mac OS 10.15.5 I find that Thunderbird 68.8.1 will freeze before fully loading. Is Thunderbird incompatible with the updated Mac OS 10.15.5? I simply cannot use Thunderbird since the fix to Mac OS 10.15.5 I installed yesterday. June 2, 2020.

All Replies (2)

I'm not aware of any issues specific to 10.15.5. I'm using it myself. Please go through the first ~10 steps of https://wiki.mozilla.org/Thunderbird:Testing:Memory_Usage_Problems

I tried starting Thunderbird in safe mode, but after a minute or two it shows up as "unresponsive" in Activity Monitor. I don't think it is a Thunderbird problem. It is a Finder or System problem. Apple Mail does not work either. Thanks for the suggestion anyway.