What is Warzone’s “unknown function” Fatal Error? How to fix

Liam Mackay
Warzone unknown function fatal error

Call of Duty: Warzone and Modern Warfare players have been hit by the “unknown function” Fatal Error code which is preventing them from joining a match or even launching the game in some cases.

Warzone’s 80s Action Heroes event officially concluded with the June 3 update. This closed the Nakatomi Plaza vault, provided bug fixes, and gave a small buff to the PPSH-41. However, this update appears to be causing an error code, with players reporting they can’t join matches or even launch the game in some cases.

Since the June 3 update, several players have been hit by the “unknown function” Fatal Error code. Players across Xbox, PlayStation, and PC are met with this code either when booting up Modern Warfare/Warzone, or when trying to queue into a game – even a Private Match.

Warzone nakatomi plaza

This Fatal Error crashes the whole game, completely stopping users from playing either Modern Warfare or Warzone. One player has reported that single-player still works, but with Season 3 wrapping up soon and Season 4 on the horizon, players will want to keep grinding to finish the Battle Pass.

There have been a ton of Reddit posts on the topic since June 3, with many players reporting that they can’t access the game. Judging from the Reddit posts, it seems to be hitting new players the worst, with many getting hit by the code in the Warzone training mode.

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How to fix Warzone “unknown function” Fatal Error

Affected players have tried a variety of methods such as running the game in safe mode, doing a scan and repair, rolling back graphics drivers, fully uninstalling and reinstalling, and signing out and back in. None of these methods are reported to have worked, so contacting Activision support appears to be the only proven solution.

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However, YouTube channel TECH SITES has offered some potential fixes for the issue on PC. There is no guarantee that these solutions will work, but the video might be of help.

“unknown function” Fatal Error solution #1

  1. Open battle.net
  2. Select Call of Duty: Warzone
  3. Click on ‘options’ then ‘Game Settings’
  4. Tick the ‘Additional command line arguments’ box
  5. Type -D3D11 into the box
  6. Click ‘done’
  7. Launch Warzone

“unknown function” Fatal Error solution #2

  1. Open ‘this PC’ or ‘my computer’
  2. Open ‘Documents’
  3. Open Call of Duty: Modern Warfare
  4. Delete the ‘players’ folder
  5. Open battle.net
  6. Launch Warzone

If this doesn’t work, you should do a ‘scan and repair’ as this will reinstall the missing files. Or, just do a fresh reinstall of the game to put Warzone back to its initial state.

“unknown function” Fatal Error solution #3

  1. Open battle.net and click on ‘Call of Duty: Warzone’
  2. Select ‘options’ and click on ‘Show in Explorer’
  3. Open the ‘Call of Duty: Modern Warfare’ folder
  4. Delete all the files in this folder except for the folders such as ‘data’
  5. Open ‘options’ in battle.net again
  6. Start ‘Scan and Repair’
  7. Wait for Scan and Repair to complete
  8. Launch Warzone

“unknown function” Fatal Error solution #4

  1. Open your PC’s ‘Start Menu’ and open the ‘Control Panel’
  2. Search for ‘System’ and press Enter
  3. Click on ‘System’
  4. Click on ‘Advanced Options’
  5. Go to the ‘Advanced’ tab
  6. Select the ‘Performance’ section and click on ‘Settings’
  7. Go the the ‘Advanced’ tab
  8. Click ‘Change’ under the ‘Virtual Memory’ section
  9. Uncheck ‘Automatically manage paging file size for all drivers’
  10. Select ‘No paging file’ underneath it
  11. Press ‘Set’ and click on ‘Yes’
  12. Press ‘OK’
  13. Close the Control Panel and restart your PC
  14. Launch Warzone

TECH SITES also included a guide on how to revert these changes if you wish to.

You simply need to:

  1. Follow the steps again until you reach the ‘Virtual Memory’ (Step #9)
  2. Tick ‘Automatically manage paging file size for all drivers’
  3. Click ‘OK’
  4. Restart your PC

While this Fatal Error is frustrating, it’s worth taking some comfort in that it appears to be an issue on the developer’s end rather than yours. Once the dev team is aware of this issue, they’ll likely be quick to get you dropping back into Verdansk and MW’s multiplayer.

If a member of the community finds any more confirmed solutions or Activision or Raven Software responds, we’ll update this article to keep you in the loop.

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Image Credit: Activision / u/Langers-

About The Author

Liam is CharlieIntel's Editor who focuses on Call of Duty but also plays lots of fantasy RPGs or anything else in his massive gaming backlog. After graduating in Journalism from Edinburgh Napier University, Liam freelanced in games journalism before joining CharlieIntel in November 2020. You can contact Liam at [email protected].