"an error occured while updating garry's mod ()"

i just got gmod as a gift after waiting for almost 2 years to play it and now after trying to download it stops at 95% first time and dosen’t let me complete downloading when i try to resume it it just seems to start downloading then an unknown error appears…
“an error occured while updating garry’d mod ()”
i tried steam support in Steam Client > Network/Connection Issue but they are so slow (+24h for a reply and still not fixed)
-i tried to reinstall steam but always the same problem
-i tried redownloading from scratch(stopped at 80% and 90%)
-i tried to change download directory
-i tried to change download region
i know this doesn’t probably have anything to do with the in game but this is really frustrating

anyone ??