If you encounter an error like the one mentioned in the title when trying to add weapons to the server and weapon are not downloading to the server, the solution is as follows.


1. go server main folder, and copy steamclient64.dll and tier0_s64.dll and vstdlib_s64.dll

2. replace steamclient64.dll and tier0_s64.dll and vstdlib_s64.dll or so files from server main
folder and place them in (server folder)/Binaries/Win64/ for windows or
(server folder)/Binaries/Win64/lib64 for linux

3. restart server(You may have to wait for a few minutes for download)

4. If it still doesn't work, download steam cmd, after extracting the Steam cmd and run it,
Copy the three files mentioned in the first step. and paste them
into the server folder's/Binaries/Win64/ for windows
or
server folder's/Binaries/Win64/lib64 for linux,
replace or overwriting.
(and after restart server)


After attempting the solution and restarting the server, even if the message in the title appears again, if there is a weapon cache folder in the server's cache folder, the download has completed normally, so please ignore it.