After checking various user reports and trying to replicate the issue locally, it turns out that there are several underlying scenarios that will cause the 6634. Here’s a shortlist of potential culprits: Now that you are aware of every potential scenario that might be responsible for the apparition of the 6634 error code, here’s a shortlist of fixes that other users have successfully used to play Call of Duty Modern Warfare without seeing this error code again.
Unequip the Watch item
As it turns out, one of the most common instances that will trigger the Dev code 6634 with Call of Duty Modern Warfare is a watch + operator combination that makes the game crash during certain in-map actions. One infamous combination that is known to cause this problem is when players attempt to use the Stitch operator with ANY Cold War watch. If you find yourself in this particular scenario and your loadout currently contains an equipped watch, follow the instructions below to attempt to resolve the issue by unequipping your Call of Duty Modern Warfare watch item: If you made this adjustment and you still see the 6634 error when you attempt to join a multiplayer game, move down to the next potential fix below.
Uninstall the MutiPlayer Pack 2 and MultiPlayer Pack 3 (Consoles Only)
If the first potential fix was not effective in your case and you confirmed that Cold War content has nothing to do with this error, the next thing you should do is ensure that you’re not deal with a common cause of a broken MultiPlayer Pack 2 or MultiPlayer Pack 3 content. This is very common on Xbox Series S, Xbox Series X, and PS5. (Consoles that allow you to partially install games) What usually happens is one of those Multiplayer packs (or both) becomes corrupted when a new update is installed and up interfering with the stability of the game. In case you find yourself in this particular situation, you should be able to fix the problem by temporarily uninstalling these 2 problematic Multiplayer packs from your Playstation or Xbox console before installing them back. Depending on your console of choice, follow sub-guide 1 or sub-guide 2 to fix the problem in your case:
Reinstall MultiPlayer Pack 2 & 3 on Xbox Series X or Xbox Series S
Reinstall MultiPlayer Pack 2 & 3 on Playstation 5
If the 6634 dev error is still an issue in your case, move down to the next potential fix below.
Cleaning the Battle.Net Cache (PC Only)
If you’re seeing the Dev Error 6634 on PC while booting the game using Blizzard’s launcher (Battle.Net), chances are you’re dealing with some type of corrupted cache issue. This has been confirmed by several users that we’re unable to join or maintain a stable multiplayer connection. Some affected users have confirmed that they managed to fix the issue indefinitely by navigating to the location of the Blizzard Entertainment folder (the one that holds the cache folder) and delete every file there in order to clear the cache. If this scenario is applicable to your current situation, here’s a quick guide on clearing the Battle.net cache in order to resolve the Dev Error 6634: If your attempts at connecting to Multiplayer games (regular, competitive or Zombie Mode) end up with the same 6634 dev error, move down to the next potential fix below.
Reinstall Game Shaders (PC Only)
According to some users that we’re also dealing with this particular issue, it’s not uncommon for this issue to be caused by a glitched shader cache that is causing the game to crash. Fortunately, you can resolve this issue fairly easily by accessing the game’s Options menu and forcing the reinstallation of the Shaders. This procedure has been confirmed to be effective by a number of users that have been dealing with the dev error 6634. If this scenario looks to be applicable to your particular situation, follow the instructions below for steps on clearing & reinstalling the Shaders Cache in Call of Duty Warzone: In case you are still seeing the 6634 dev error when attempting to join a multiplayer game, move down to the final potential fix below.
Uninstall the game and install Warzone ONLY
If none of the potential fixes above have worked in your case and you’re experiencing this issue with Warzone, you should be able to avoid the issue completely by uninstalling the game and strictly installing Warzone – without the single-player campaign, zombie mode, or multiplayer component. This is certainly limiting if you enjoy playing multiple Call of Duty modes, but it’s a fix that a lot of Warzone players have successfully deployed on both PC and consoles. Whether you’re a PC or console gamer, follow one of the sub-guides below to uninstall your current Call of Duty installation and install the standalone version of Warzone:
Uninstall COD and install Warzone (standalone) on PC via Battle.Net
Uninstall COD and Install Warzone (standalone) on PS5
Uninstall COD and Install Warzone (standalone) on Xbox Series X / S
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