[Bug] Cannot colonize planet

Had the same thing. I assumed it was something I didn't research, but who knows...

Rats!  I quit the game, loaded the saved game that I posted a link to above, and now the problem doesn't happen.  So the saved game won't help track down the problem.

I had the same as well, also sorted out by save and reload

Later in the same game, different planet, different colony ship, same problem.

I've just experienced this bug when I sent a colony ship to a empty planet that already had a further away colony ship en route, my closest one couldn't colonize but then my further away (and originally destined) colony ship could the same turn when I manually moved it afterwards.  

That's interesting, but perhaps a separate problem from mine.  In my case I only had the one colony ship when trying to colonize the planet.

Same here and save and reload didn't fix the problem. It was a normal planet and a few turns later the Alterans took it, while my CS went to a different system and colonized that.

Same problem here. It appears to occur when the AI sends a ship to colonize the same planet.

I have had it happen on several different planets.  When I use auto save to go back usually one or two turns the ship will colonize the planet when the game moves forward.  I thought originally that the planets were too far outside my influence but using auto save to reload has allowed my ships to colonize the planet on 4 different occasions in the same game.

Hmmm.  In my case the AI had sent several colony ships towards these planets, and I had blasted all of them into oblivion.  But perhaps the mere act of sending one causes the problem.

I have encountered this same error! I once clicked "no" to the "Do you want to colonize a planet" screen by accident. I had sent three colony ships to colonize a system of three stars. and by luck they all arrived at the same time. I accidentally clicked no to the first one. The other two, which arrived at the same time, where able to colonize on that turn. But I was not able to colonize any more planets. Interestingly, the others could still colonize other planets except that one that I said "no" to on accident--I was able to kill some Drengin colony ships that just stopped in the adjacent tile. 

This error has been tracked down, thanks to the alpha testers, and should be fixed in next build. It was caused by multiple races targeting the same planet while out of range of the planet. 

Woo-hoo!  We got a bug!

I'm sorry but, this isn't the cause...  In my current game I started with only 1 AI player, the AI player never had more than the initial colony ship.  AI colonized the planet in the system, I took the home planet via transport w/ in 5 turns.  They have since never launched another colony ship.  Two planets in a completely different system will not allow colonization.

In order for that to be the only reason this is occurring it would mean that the AI player targeted both planets prior to colonizing the planet in it's system or has phantom colony ships ready to colonize said planets... 

Just thought I'd share this bit of information.

I think this might possibly happen with your own colony ships too, at one point I had 2 colony ships going to the same planet. When the first arrived it could not  colonize. So I sent it to the next planet nearby and used the ship.  When the second colo ship arrived the next turn it could colonize the first planet just fine.

Also, in the game we played I might have sent a Colo ship to the class 24 planet before you tried colonizing it. But then made it turn around when I saw you beat me to it.

Wasn't the cause in the single player I was just playing, first colony ship sent to each planet.  Tried with both after I couldn't colonize to go to the other planet and neither could colonize either...  So even though multiple players trying to colonize the same planet might be one but with colonization I don't think it's the only one.

This seems to make sense, because in the next couple of turns the Drengin colonised the planet...