3475403 - ASE upgrade failed due to error 4237 "Cannot dump master database's log as distributed transaction resolution is not complete yet." - SAP ASE for Business Suite

• ASE upgrade failed with error 4237 "Cannot dump master database's log as distributed transaction resolution is not complete yet. Please retry later" when running installmaster script in post ASE upgrade step:

# ./saphostctrl -function LiveDatabaseUpdate -dbname <SID> -dbtype syb -updatemethod Execute -updateoption TASK=UPDATE_ASE -updateoption DROP_LOCATION="/usr/sap/..."
Error: Command execution failed. : Server message: Number 4237, Severity 16, State 1, Line 2, Server SID --- Message string: Cannot dump master database's log as distributed transaction resolution is not complete yet. 
Please retry later. . (fault code: 127)

• The last line in LiveUpdate.log:

UPDATE_ASE_POST_CONFIG=Failed to execute installmaster

• Trying to check distributed transactions in ASE got error 950 saying that database sybsystemdb is offline:

1> sp_transactions
2> go
Msg 950, Level 14, State 1:
Server '<SID>', Procedure 'sp_transactions', Line 63:
Database 'sybsystemdb' is currently offline. Please wait and try your command again later.

• ASE errorlog file shows error 15497/975 reported earlier indicating previous recovery failure for database 'sybsystemdb':

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Error: 15497, Severity: 16, State: 1
The password for the master key of database 'master' has not been set.
Error: 975, Severity: 17, State: 1
The database 'sybsystemdb' is encrypted.
Unable to proceed with the recovery of dbid <31513> because of previous errors.
Continuing recovery with the next database.
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• SAP Adaptive Server Enterprise (ASE) 16.0 SP03 PL9 for Business Suite
• SAP NetWeaver (NW) - All versions 

Error 4237, 4237, CR 828369, 828369, dump mater database, dump master database's log, distributed transaction resolution, saphostctrl, ASE upgrade, installmaster, Failed to execute installmaster, 15497, 975, 950 , KBA , BC-DB-SYB , Business Suite on Adaptive Server Enterprise , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Problem