Hello there @Yayalegoatoffi!
No worries, you described the issue perfectly. These errors confirm map load issue, most likely tied to corrupted data:
Assertion failed: Export.ScriptSerializationStartOffset == (Tell() - Export.SerialOffset)
Serialized script property end offset does not match offset during deserialization
So, the first step here would be to clear your project’s cache, to get rid of any invalid data. Close UE, then go to your project’s directory, and delete folders Intermediate, Saved, and DerivedDataCache. Afther that, re-open your project and load your map.
If the issue persists, test by opening a different map between your project, in order to pinpoint the issue’s origin. As well, if the crash started after any specific change, try to re-roll your map to a previous version, using a backup from Saved/Autosaves/Game/Maps/
We could also use the full crash report, for reviewing. Crash reports from the editor are stored on your local machine in your project’s Saved/Crashes folder.
Additionally, please check the solutions implemented in the thread below: