'Package - Version Mismatch" typically means the map file the server has installed doesn't match the map file from the location it downloads for players when they connect. (Workshop or Redirect) It's usually a server related problem but not always.

• Workshop uploaders renaming their map filenames after updating their map will cause a mismatch error for server owners. For example KF-MapNameV1 was changed to KF-MapNameV2. Mappers need to avoid changing the filenames of their map if they plan on updating their existing map to the Workshop.
  
  
• Workshop maps that were recently updated but the server hasn't download the latest version yet will cause a mismatch error. If you're running Steam and your dedicated server on the same computer, close steam and launch the server to update maps if it didn't do automatically. If it still won't update, scroll down and read fix #5.
  
  
• Redirect maps that share the same filename but are different file sizes will cause a mismatch error. For example, you have KF-BikiniAtoll 45mb installed in your KFGame/BrewedPC/Maps folder, however on the map redirect KF-BikiniAtoll is 65mb. Therefore, the server has KF-BikiniAtoll 45mb loaded but when players connect, it's trying to download KF-BikiniAtoll 65mb. Check fix #2.
  
  
• Custom map files in your My Documents path can potentially cause a mismatch if the filename is the same as the one you're joining but the versions are different. Check fix #1
  
  
• Tampering with Workshop maps inside the main installation path of Killing Floor 2 (Program Files (x86)/Steam) can potentially cause mismatch errors for yourself only. Check fix #6

1. Clear Cache Map Files You've Downloaded - This is generally the first thing you want to do. You can delete the entire folder or select certain numbered folders which are the Workshop ID numbers of each map. If this doesn't work, then the errors are server-side and we will continue on!
   
   C:\Users\Your User\Documents\My Games\KillingFloor2\KFGame\Cache
   
   
2. Redirect Mismatch - If your custom maps are downloaded from a redirect like http://skillzservers.com/kf2-redirect/ be sure the custom maps on the redirect are identical to the custom maps you have installed in KFGame\BrewedPC\Maps\ of your dedicated server. Check the file sizes to be sure they match!
   
   
3. Workshop File Renamed - If your custom map is downloaded from the Workshop, be sure the .kfm custom map file did not get renamed by the mapper when he/she updated it. You can check by going to the location of downloaded Workshop maps of your Server. (Cache folder)
   
   KF2ServerKFGame/Cache
   
   The numbers in the Cache folder represent Workshop ID numbers of each map. You can either search for a name by typing KF-*.kfm (with the asterisk) or search the Workshop ID like 643383080.
   
   Next, check to see if the filename is the same as the one you originally entered into your PCServer-KFGame.ini file. If the filename has changed, you'll get a mismatch error.
   
   
4. Workshop Map On Your Server Needs Updated - If your custom map is downloaded through the Workshop, be sure it is up-to-date with the latest version. You can check the release date of the update on the Workshop page compare it to the date of the file your server has installed.
   
   
   
   If you run your dedicated server on the same machine you run Steam, close Steam and launch the server. There's a bug that prevents maps from being updated with Steam is running. Wait a couple minutes for it to download any map updates. If that doesn't work, proceed to #5.
   
   
5. Workshop Map Not Updating - If your custom map is downloaded from the Workshop and will not automatically update, you will need to delete all traces of this map from your server files.
   
   a. Copy the Workshop ID of the problematic map and paste it in the search box inside the KF2Server folder. You will see 2 numbered folders popup which is the map you want to delete. It will show 2 folders because it's coming from 2 locations. Delete both folders then continue to the final step.
   
   b. Delete Folder From First Location
   

   C:\KF2Server\Binaries\Win64\steamapps\workshop\content\232090

   c. Delete Folder from Second Location
   

   C:\KF2Server\KFGame\Cache

   
   Important: If you only delete the map from the Cache folder, the server will automatically copy the SAME version you just deleted back into that folder, thus not updating the map. You will need to delete the map from BOTH locations above AND continue to the next step into order to get the map to update.
     
   d. Next step is to locate appworkshop_232090.acf by going to:

   KF2Server/Binaries/Win64/steamapps/workshop

   
   e. Open the appworkshop_232090.acf with Notepad++[notepad-plus-plus.org]
   
    
   f. Inside appworkshop_232090.acf, search for the workshop ID and delete the entire section for the problematic map. If there's two listings of the map, delete both. I have highlighted a section to delete as an example.
   
    
   Note: if you have multiple maps failing to update, you can delete the entire appworkshop_232090.acf file and it will recreate a new one when you launch the server. However, you should delete all map folders as well if doing this.
   
   g. Finally, launch your server and let it download new copies of the maps. Mismatch error should be fixed.
   
   
6. Non-Server Related Mismatch Error - There are some cases of mismatch errors that are still unsolved and have absolutely nothing to do with the setup of the server they're joining. If you cleared your cache folder in my documents and you're sure the server is not the problem, you may need to reinstall Killing Floor 2 or verify the integrity of the game files.

Downloading Package - Error Opening File usually means the server cannot fetch the map file for players connecting to the server or there's some conflict with the file. It's a common problem with maps setup through a redirect but can occur with Workshop maps too.

• Redirect: The .kfm map file you have installed in KFGame/BrewedPC/Maps does not exist on the map redirect you specified in your PCServer-KFEngine.ini config. Players cannot connect to your server if the map redirect does not provide the map file your server is running. You will need to upload the map file to the redirect so players can download it.
  
  
• Redirect: Map redirect was never specified in PCServer-KFEngine.ini. Even if you have correctly installed the map to your server files, players still won't be able to connect if there's no web server to download the map.
  
  
  
• Redirect: Filenames are case-sensitive. Ex. If you installed KF-Vava.kfm but your Map Cycle uses KF-vava, you will get an opening file error. Be sure the map name in your .ini config matches the filename exactly if using a redirect for custom maps.
  
  
• Workshop: Server cannot connect to the Workshop to download the map because you're missing this line under [IpDrv.TcpNetDriver] in your PCServer-KFEngine.ini file
  

  DownloadManagers=OnlineSubsystemSteamworks.SteamWorkshopDownload

  
  
• Workshop: The map was never installed. Check if the server downloaded the map to the cache folder.
  

  C:\KF2Server\KFGame\Cache

  
  
• Workshop: Map entry is missing from the PCServer-KFGame.ini file.
  

  [KF-BikiniAtoll KFMapSummary]
  MapName=KF-BikiniAtoll

  
  
• Workshop: The file was removed from the Workshop or made private. You cannot load a custom map from the Workshop if this is the case, even if you had already installed the map prior to it being taken down.
  
  
• Client Side: There may be maps located in C:\Users\Your User\Documents\My Games\KillingFloor2\KFGame\Cache conflicting with the download. Delete that Cache folder to clear out all downloaded maps. Make sure there's no files in the Published or Unpublished folders that may cause conflict.
  
  
• Client Side: I will throw this solution in as well but it usually applies to other opening file errors, not for custom maps. You can try to Verify Integrity of Game Files.
  
  
• If all else fails, there's a problem with the .kfm map file or it's missing additional .upk files to properly load.

Duplicate UID error basically means the server thinks you're already in the server. Usually happens when you try to join a server twice and two of the same ID can't play on the server. UID likely stands for Unique Identifier.

You'll have to wait around 2 minutes more or less for the server to clear you out. It can also be fixed by the server reloading the map.

When you vote for a custom map and it loads KF-BioticsLab instead, this means the server could not find the map file you specified in your PCServer-KFGame.ini config. Be sure you made no spelling mistakes AND the map file is fully installed.