When I try to give any thing to Katja using the steal method, I get a message that says "there is no room for that item"
The only thing she's carrying is one stimpack and 6 throwing knives. Even if I take those away, I still can not give her any items.

Thanks, that worked. Never thought to use the barter. Have always used the steal opition to give and take from the NPC's. New at this. Thanks again.

No problem. I wasn't sure if you were trying to use some trick but barter is the give button in fallout between yourself and the NPC's.

Using the barter interface in Fallout to give things to companions is basically cheating because it ignores their carry weight allowing you to give them unlimited weight.

Sorry to necro this topic, but this is happening in my game. I'm using the TeamX 1.2.1 + 1.3.5 and high res patches, and I don't recall this happening before. I've previously played the game without unofficial patches and with the TeamX 1.2 patch and child restore patches. We just fought the super mutant guards at the military base. She used some stimpaks during battle and I tried to give her more, but it said there was no room. She shouldn't have been full because she used ammo and stims during battle and she was not full before combat. I have only used the steal skill to exchange items during the game.

I removed all of her items and gave her a bunch of 1lb items until it said there was no more room, and she is now only able to carry 21lbs of items. She should have a carry weight of 125 lbs. She does not have any crippled limbs or other status effects, I would be able to see if she did because I have the awareness perk.

I tried to load earlier saves to see when it started, and it seemed to have started happening right when I arrived at the military base. Any save before that doesn't have this problem. I'll have to use barter now unless someone knows what is causing this and how to fix it.

I just discovered the problem and the solution. I looked more closely at the save before the problem started the one after and discovered that wearing power armor is causing it. If I have power armor on I can't give Katja items, if I remove the power armor I can giver her items. It's as simple as that.