Having problems running the program itself after update

You must have tried to update from Tiled 0.18.0 or earlier to a later version. Due to a change in the way the Tiled installer works, it is not able to do this upgrade correctly, but I did not find a way to avoid this problem nor to prevent users from running this upgrade. Hence I wrote a warning in the 0.18.1 and 0.18.2 release notes, but maybe it was too early to remove this warning…

In any case, you can fix this by uninstalling all versions of Tiled and then re-installing 0.18.1 or later (I recommend 1.0.1 of course).