UE 5.7 PSO Cache Hash Mismatch: "PSO from the cache was not found"

Development Programming & Scripting
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1

Since migrating to Unreal Engine 5.7, we are encountering an issue where pre-gathered PSO caches included in the package are seemingly ignored or mismatched.

The log repeatedly shows: Warning: PSO from the cache was not found in the cache!, which forces the engine to re-collect PSOs at runtime causing hitches.

We have tried the following steps to resolve this:

  1. Gathered new PSOs using the 5.7 build.

  2. Performed a completely clean wipe (deleted Saved, Intermediate, and Build folders).

  3. Repackaged with the freshly gathered .spc file.

However, the issue persists. Even if we include the newly collected PSOs, the engine still reports them as “not found” in the subsequent package, creating an infinite loop of re-gathering.

We did not have this issue in UE 5.6, and our packaging environment/workflow has not changed since the migration.

Has anyone else experienced this issue in 5.7? Is there a known solution or workaround?

// Example Log
LogRHI: Warning: PSO from the cache was not found in the cache! PSOHash: