3407293 - A1EEGEN 000 File 'EUEXPORT_00XXX.xxx' not found during DMO import, although the file exists

During SAP system upgrade using SUM DMO, sometimes the below error could happen at EU_IMPORT phase:

2EETQ106 24 processes failed.
1EETQ399 Import task 'load/eu_import/EU_IMPORT_00077.CMD' has errors, exit code 12. Check 'load/eu_import/EU_IMPORT_00077.LOG'.
1EETQ399 Import task 'load/eu_import/EU_IMPORT_00033.CMD' has errors, exit code 12. Check 'load/eu_import/EU_IMPORT_00033.LOG'.
1EETQ399 Import task 'load/eu_import/EU_IMPORT_00059.CMD' has errors, exit code 12. Check 'load/eu_import/EU_IMPORT_00059.LOG'.

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Further check the corresponding EU_IMPORT_XXX.LOG (as mentioned in the error message), will see error message similar to:

A1EEGEN 000 File 'EUEXPORT_xxxxx.xxx' not found

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After checking the tmp directory, the EUEXPORT_xxxxx.xxx file (displayed in EU_IMPORT log) exists, but still the SUM tool shows this "EUEXPORT_xxx.xxx not found" error.

(Note: The above displayed process number and task number including 24,77,33,59, and xxx are only for examples. In real situation, the task number could be different.)

SAP AS ABAP system.

SUM, DMO, EU_IMPORT, EUEXPORT, A1EEGEN 000 File 'EUEXPORT_xxxxx.xxx' not found, tmp, absolute path, relative path. , KBA , BC-UPG-TLS-TLA , Upgrade tools for ABAP , Problem