Hello there @HeliusCarthaxis!
The error you are getting suggests the engine is having a problem when accessing a particular shadow map from your scene. When UE tries to remove this shadow from the cache, and said shadow is nowhere to be found, the whole thing crashes.
This is mostly due the shadow cache being overloaded and running out of space, and it only happens in the packaged build because the editor has more memory available, hidding the issue. And the first thing I would check, is about running r.Shadow.TexelsPerPixel at 16.
That value translates into having every actor in your scene generating shadow maps 16 times larger than usual, which will result in a guaranteed overload. I would test setting it to 4, or even 2. Yet, if the issue persists, try by defaulting it back to 1.
On the other hand, we can increase the engine’s capacity to handle your shadows, by increasing the cache limits. User the following cvars, or add them to your DefaultEngine.ini file:
r.Shadow.MaxCSMResolution=2048
r.Shadow.WholeSceneShadowCacheMb=200
One more thing to check, is how many of your actors need to cast shadows in the first place, as every single object in your level under a stationary light can contribute to the issue. If there are any elements that can work with no shadows, simply select them, go into their details panel, and uncheck “Cast Shadow”
After applying these steps, test by repackaging your build, and see if the crash remains active. Hope this helps, and good luck!
