I updated all installed docsets. The next time I restarted Zeal it was from command line, which allowed me to notice this message:
Could not load docset from '/home/<user>/.local/share/Zeal/Zeal/docsets/Python_3.docset'. Reinstall the docset.
But when I did so, I get this:
[1] 10547 segmentation fault (core dumped) zeal
Using 0.4.0 on Ubuntu Xenial (16.04) 32 bits.
I checked after removal of the old Python_3.docset directory, I can reinstall it without any crash, so that鈥檚 something which was in this directory which made Zeal crash. I made a back-up of that broken directory before removing it : see the attached archive below.
I can reproduce the crash, thanks for reporting, and the corrupted directory sample!
I dont know why updating this docset causes error:

@duytrung Your problem is unrelated to this ticket, see #775.
Another corrupted docset if you need it. Have been trying to download docsets over a really bad internet connection, which has lead to a lot of failed downloads and possibly the corrupt docsets (was downloading with an older version of Zeal [0.3,1 from the ubuntu repositories]), which has been a pain with a docset as big as the Javascript one. Might try manually downloading them from the server (https://github.com/Kapeli/feeds has the list of feeds for anyone looking for it) and then putting it in the correct place.
@bytesnz thanks! I've narrowed it down, the fix is coming.
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I can reproduce the crash, thanks for reporting, and the corrupted directory sample!