hi @Bil_game78 ,
There was an article about picking out code and translating
Asset Validation Issues - Issues and Bug Reporting
So the extracted bits to paste in the Outline window is
2RVTAOI30XZ1U9AMBH9WOK
ZOJTLKMXTMQ8IBA19KOWT0
This should show the Asset that is failing
Experience shows this is due to project in a prior version for example 29.60
This next command could cause more problems and on do it if you are comfortable
The way the fix this is delete the content of the store in Windows File explorer
C:\Users%USERPROFILE%\AppData\Local\FortniteGame\Saved\PersistentDownloadDir
to completely rebuild UEFN stores will attempt to build the corrupted store
READ THE WARNING and if you are not comfortable with advanced troubleshooting dont use this
if you type something wrongly you could do severe damage always use copy/paste commands