Hi, we have encountered an issue where we cannot consistently launch a UE 5.1 without it crashing with errors. We can run the project without a problem on a couple of our dev machines. But the issue persists in 2 of our client PCs that we tested out.
We have tried
Fresh epic launcher install → install UE 5.1.1 → launch and create empty project, works fine.
Then, close and reopen the project crashes with the error:
That’s quite a tricky scenario, as even fully wiping the affected PCs did not solve the problem. Which means, there’s an element that is reintroduced to the system, even after full format.
Now, the error you are getting, is tied to a HashTable conflict. Checking around the community, these are usually tied to data corruption, or rights conflicts. Since you fully cleared the system, and empty projects are working as intended, the engine’s cache should be fine. On the other hand, the older project may have carried over corruped data from the other systems.
So, the first step is to clear the old project’s cache. Open it’s directory, and delete folders DerivedDataCache, Intermediate, and Saved. Now, the next time you start the project, this will be re-generated. If this was the problem, it should be solved at this point.
But if the issue persists, then we have the other path, write permissions. Since these are client PCs, they most likely include extra security measures, which could affect the engine’s capacity to write and update the DDC. Please make sure these system have full rights for the project’s location, UE’s AppData folder, and the engine’s install directory. Additionally, consult if any security features could affect the functionality of the processes involved ( UnrealEditor.exe, ShaderCompileWorker.exe, etc).