Created attachment 8706135 [details] shell output when problem becomes manifest Lightning doesn't work on Linux if the partition comprising /home has mount option "noexec" set. Right after launching a dialog "Mismatching Lightning Version" comes up stating that the versions of Lightning and Thunderbird don't match. The UI of both Lightning and Thunderbird gets compromised and the X server is using the CPU nearly 100%. Problem seems to affect the launch only as it cannot be seen if mount option noexec is not set when Thunderbird gets launched but only gets set by remounting the partition while Thunderbird is running. Seen on Arch Linux i686 and x86_64 running matching Thunderbird 38.5.1 from releases.mozilla.org. Output running Thunderbird from the shell is attached.
This is expected. Lightning has a binary component, it will not work correctly with noexec. So please make sure that the device is mounted with the exec flag.
In 2007 (Bug 383653) it was suggested to add this information to FAQ but this was not done because nobody reads them after all.
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