How To Fix ‘Serialization Error Action Needed’ in Ready or Not

The Ready or Not error “Serialization Error Action Needed” is typically accompanied by the text “Corrupt data found, please verify your installation.” It’s an Unreal Engine error, and there are a few possible ways to deal with it.

1. Verify Your Installation

The first thing to do is to do what it’s asking, verify your installation. To do so, go into Steam and to the following. Make sure you’ve not set Steam to offline mode.

• Go to your Steam Library and find Ready or Not.
• Right-click on it and select Properties.
• Click on Installed Files
• Click on Verify Integrity of Game Files

This will check if any files are missing or damaged. If Steam does find any missing or damaged files, it’ll re-download them. Now, try Ready or Not again, and if it works, you’re good. However, the problem may be more complicated, in which case you’ll need to do something else.

2. Remove Any Mods

The “Serialization Error Action Needed” error message can be caused by Ready or Not mods that are out of date or otherwise broken, often because they haven’t been updated to work with Unreal Engine 5. To delete mods, do the following (via CosmoCart):

• Go to your Steam Library and find Ready or Not.
• Left-click on Manage and then Browse Local Files.
• Now, double-click on the ReadyorNot folder.
• Double-click on the Content folder.
• Double-click on Paks.
• Delete the mod.io folder (left-click on it and hit the delete key or right-click and select delete).

The game should now run, but that’ll leave you without your mods. So, what do you do next?

Related: Ready or Not: What’s Better, DirectX 11 or DirectX 12 (DX11 vs. DX12)?

3. Reinstall Your Mods

The next step is to reinstall your mods and reinstall them one by one. Go to Nexus Mods, Mod.io, or wherever you got your mods from, and find the page for the mods.

Don’t install anything yet, though. Look around the page to see when it was last updated. If it was updated later than July 2024, which is when Ready or Not went to UE5, install it. If it hasn’t been updated to work with UE5, you won’t be able to use it.

Install a mod, try running the game, and repeat this. If the error crops up again, you know that the last mod caused the error, and so you’re going to have to skip it. Sorry, but if the mod hasn’t been updated to work with the Unreal Engine 5 version of Ready or Not, you simply can’t use it.

If all else fails, uninstall and reinstall Ready or Not from scratch. It’s also possible that your hard disk has become corrupted, but most reports of the error stem from out-of-date mods. And that’s how to fix “Serialization Error Action Needed” in Ready or Not.

Ready or Notis available now for PC.