Hello,

I was able to find the reason. If you look closely at my screenshot you see blue marked ground area just left of the red outline of the Outpost. I had to shift around some walls to make enough space for it but it worked.

However I was not able to find out why some areas are blue and others aren't. It has nothing to do with cooling towers, power lines or anything else.

If anyone has an idea what it is I'm sure this would be helpful for future reference.

Looks like the outpost also acts as a local Rift Portal, and it's too close to the portal you can see on the right.

I've just observed this behavior myself. I removed the portal and could construct the outpost building afterwards.

I haven't tested this myself to verify, but I have read that as an Outpost building also counts as a portal, it cannot be built nearby a regular rift portal.

It's the same deal when placing rift portals - they cannot be located too close to each other.

That makes sense. On my screenshot you can see a regular portal on the right. And it was a fairly small base because it is in the lava biome and I did not want to build too many of these cooling towers.

Thanks for the replies.

If you sell the rift portal to the right on the image, or move the cursor to let the building hover over the blue squares (as you have it in the black area on the screenshot, inside the existing portal zone), you should be good. :)

This is something I have found annoying on several occasions - the game really isn't good at explaining what is wrong. It basically only says "You cannot do that!" (like placing the Outpost in your case), but it rarely, if ever, explains why or what can be done about it.