In one of the environments (19c) after successfully applying Oracle patches at binary level, the following error was thrown when datapatch command was executed:

Error: prereq checks failed!
patch XXXX: XML descriptor does not exist in either the file system or SQL registry
Prereq check failed, exiting without installing any patches.

Please refer to MOS Note 1609718.1 and/or the invocation log
/opt/oracle/cfgtoollogs/sqlpatch/sqlpatch_16524_2025_01_31_14_35_22/sqlpatch_invocation.log
for information on how to resolve the above errors.

so the tool was searching for an old patch that doesn’t exist anymore under $ORACLE_HOME/sqlpatch directory.

— Possible Solutions:

Possible solution 1: if the patch number XXXX is related to old java patch, then apply latest OJVM patch…you can execute the following command to check:
$ORACLE_HOME/OPatch/opatch lspatches

Possible solution 2: copy the missing patch folder from another database environment to this environment (the environment you are facing the error) , under this folder: $ORACLE_HOME/sqlpatch