Please try these troubleshooting steps:
- Try packaging a blank, Third Person Blueprint template. Can you package this successfully? If so, move to step 2. If not, provide entire packaging log,
- If you can package a Blank, Third Person Blueprint project, try disabling Chunks under Project Settings>Packaging
- Delete the Boot.dcc file from the DerivedDataCached folder located in the Engine’s install directory.
- IF a Blueprint only project, add a blank C++ actor and try packaging again
- Disable all plugins and try packaging again
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