Stripped bolt with Koni Yellows(Rear)

Started on installed Koni Yellows in my car but ran into a problem. The rear struts either have terrible threading at the welded nut, or my OEM bolts were bad. Took my time to line everything up but as I tightened the bolt, the bolt was completely stripped when I removed it. I tried to run the OEM bolt through the other rear strut as well ,but it got stuck after a few turns. Has anyone run into this problem before?

Its most likely the bolt. Go buy new oem rear strut bolts at the dealer or online, I think theyre like $10 a bolt. I just recently bought 1 as well and it tightened easily.

An odd thing occurred. When I went to go rethread the other rear to ensure the path was clean for the bolt, it ruined the thread tool. I’m thinking maybe the nut that they welded isn’t the correct size. The thread tool was at the rear LCA bolt size M10 1.25 pitch.