2602166 - SUM: Error in phase CREATE_UPGEVAL - FILE_IO_ERROR

You are performing system update or upgrade with SUM.

• Symptom 1:

An error occurred in phase "CREATE_UPGEVAL".

CREATEUPGEVAL.LOG:
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2 ETQ373 parameter "FILENAME" = "/xxx/SUM/abap/tmp/UPGANA.XML"
1EETQ235 Call of function module "SUBST_SLANA_STORE" by RFC failed (error-status "5")
2EETQ360 RFC of "SUBST_SLANA_STORE" failed:
2EETQ361 code/exception : 5
2EETQ362 key : FILE_IO_ERROR
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• Symptom 2:

An error occurred in phase "MAIN_POSTCLEAN/SUBMOD_EVALUATE/CREATE_UPGEVAL".

The error is as below.

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Severe error(s) occurred in phase

MAIN_POSTCLEAN/SUBMOD_EVALUATE/CREATE_UPGEVAL!

Last error code set:
RFC system <SID> nr 00 function 'SUBST_SLANA_STORE'
RFC failed with code 5 key ILLEGAL_FILENAME:

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System updates executed by SUM tool

DIR_PUT, DEFAULT.PFL, AL11 , KBA , BC-UPG-TLS-TLA , Upgrade tools for ABAP , BC-INS-AS4 , Installation and Upgrade AS/400 , Problem