I have Kdenlive 17.12.1 with MLT 6.6 and ffmpeg 3.4 on Arch Linux. With GIF selected as the output format, rendering crashes with the following error: 'Formats with a palette require a minimum alignment of 4' This also happens with the AppImage version of Kdenlive 17.12 downloaded from the official website. I notice that the shotcut developer has stated that this is a limitation with newer builds of MLT: https://forum.shotcut.org/t/gif-export-fails-on-v17-10/3013/2 I imagine this means that Kdenlive will simply remove support for this feature? Of course it would be nice if the feature could be retained somehow. Either way, it isn't good to leave this error message!
I exported GIF with Version 18.08.3 and it works. If you like to have a non looped GIF: Create a custom profile with this settings: properties=GIF loop=-1. We closed this bug. If it still appears in the latest version, please feel free to re-open it and update the affected version number.