Recently I noticed my Windows directory had bloated up to over 52GB, which seemed utterly obtuse. I ran TreeSize to establish where all the space on my paltry 128GB SSD had vanished to and noticed that I had around 4000 files in c:\windows\system32\config taking up about 20GB of space.

I opened the directory and noticed a couple of files with the extensions .regtrans-ms and prefixed with names of registry nodes. Ok, I tell a lie, I say “a couple”, and I mean about 3000 files - ouch.

So thinking “that sure looks legit”, I did a bit of googling around the subject. RegTrans files are registry transaction files left to supply rollback positions but there’s no clear guidance as to if it’s safe to delete them or not anywhere on the internet.

Evidently, if you do, you’ll loose any rollback’ing, but I decided I’d take the chance and get my disk space back so went for it, and thankfully everything seems fine.

So yes, if your windows install seems to have bloated beyond belief with .regtrans-ms files, feel free to nuke them.