KF2 Dedicated Server Workshop Update Failure (2025 Fix)

Since mid-July 2025, Killing Floor 2 dedicated servers have been unable to update newly published Workshop content. This page explains the cause and the community workaround. If your server is not set up yet, start with the dedicated server setup guide.

The problem

Every mod (map, pack or mutator) compiled or created since 11 July 2025 fails to update on the server side. Clients are not affected.

Why it happens

• Around February 2025 or earlier, Steam added support for ZSTD compression, a faster and more efficient algorithm than the previous LZMA, for certain data chunks to speed up downloads.
• The latest Steam DLLs in SteamCMD (version 9.86.62.31 from 27 June 2025 at the time of writing) are confirmed to work with new Workshop items, presumably because they understand the ZSTD chunks.
• On 11 July 2025 the Workshop apparently began storing new content as ZSTD chunks.
• The KF2 dedicated server ships with old Steam DLLs that cannot read the new chunk format, so downloads fail.

The real fix is a new dedicated server release from Tripwire with updated Steam DLLs. Until then, replace the DLLs yourself.

Short-term fix on Windows

1. Run SteamCMD so it updates itself.
2. Copy these files from the SteamCMD directory:
   • steamclient.dll
   • steamclient64.dll
   • tier0_s.dll
   • tier0_s64.dll
   • vstdlib_s.dll
   • vstdlib_s64.dll
3. Paste them into your server's Binaries\Win64 directory and confirm replacement.

Short-term fix on Linux

The author does not use Linux and could not test a solution, but suggests the following:

1. Run SteamCMD to update it.
2. From the SteamCMD linux32 folder copy crashhandler.so and libtier0_s.so; from linux64 copy steamclient.so.
3. Place them in the server's Binaries\Win64\lib64 directory. You may first rename the old files to .so.old as a backup.

Back up the original DLLs before replacing them, and remember that a normal server update may overwrite them again.