Quick update I went to the sevenzipsharp site and there isnt a proper bug submittion option there just a forum full of an unanswered concerns and bugs. Seriously not even one post with a staff reply, and at least 6 ppl there having the same issue with NMM and some getting the same message with steam installations, game saves, and workshop submissions. So I dont think they wil be much help. I dont even no what they mean by "post release number" and I really doubt anyone there will answer any questions. I double checked to confirm I have the latest verion on NMM, and that NMM is using the lastest sevenzipsharp.dll. I replaced the dll with a fresh download, just to eliminate the possiblity of a corrupt dll file. Tested the standalone 7-Zip file, and was able to verify, browse, extract, and recompress this archive without any errors. Tried using the recompressed version with the orginal name though NMM via "add mod from file" option. No progress