Latest release of alacarte (3.11.91) does not support python3. The code is not far from supporting it, but running under python3 does produce fatal errors.
Patch submitted to upstream adding python3 support: https://bugzilla.gnome.org/show_bug.cgi?id=787490
This bug appears to have been reported against 'rawhide' during the Fedora 28 development cycle. Changing version to '28'.
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This was retired on rawhide. I don't any point in tracking this for any lower Fedora versions.