2543304 - iseries: XDNFileTokenAuth::SendChallenge: WriteTokenFile Failed

calling db_connect ...
Loading DB library 'C:\usr\sap\<SID>\D<XX>\exe\dbdb4slib.dll' ...
Library 'C:\usr\sap\<SID>\D<XX>\exe\dbdb4slib.dll' loaded
Version of 'C:\usr\sap\<SID>\D<XX>\exe\dbdb4slib.dll' is "749.05", patchlevel (0.301)
dbsldb4:dev_trace_switch: Called with trace level 1, last trace level is -1
DB4 SQL Reparse Activated
Windows 2008 R2 - XDN Default --> the clue!
NOTICE: da_cache_size set to default=100 (set to -1 to disable)
  
Thu Sep 14 10:22:44:847 2017
 *** ERROR =>     > QxdaConnectEDRS() failed
 [dbsldb4dbi.c 378]
 *** ERROR => CPDA0FF occured: XDNFileTokenAuth::SendChallenge: WriteTokenFile Failed.
 Library xdnxdaapi.dll path: C:\usr\sap\<SID>\D<XX>\exe\xdnxdaapi.dll
 Library xdnxdaapi.dll version: 7490.0.301.806
 XDN Patch Level: 301
 *** ERROR => === Central DB connect FAILED! ===

_______________________________________________

This error was also observed during SUM2.0 SP24 Conversion to S/4HANA DMO with system move from ECC on IBM-i  

The same solution applies in this case.

NTLOGON, os400, iseries, token file, CPDA0FF, XDN, Qxda, setdb4pwd , KBA , BC-DB-DB4 , DB2 for AS/400 , Problem