this morning i tried to abandon a colony on my terran, but somehow it didn't work... i went through the abandon process, till i got the abandon colony-screen, but still have that colony...
password was correct, but i found the problem now... there was still a fleet underway FROM that planet... after it deployed on another planet everything worked fine, but thank you^^
would be cool if an error message could indicate that... ;)
4star0th, if is this planet your capital planet, its cannot be deleted. In case this planet in not your capital, just try open your game in other device and repeat the delete.