Distribued Processing in Ediscovery/Summation will not start. There is an error in the C:\ProgramData\AccessData\PM\10\logs\ProcessingEngine_Error.log Unable to write to case path.The user name or password is incorrect.
You must make sure that the service account can successfully authenticate with Kerberos with the server alias. Add a service principal name (Kerberos alias definition) to the server.
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Using Kerberos authentication with DNS server aliases was causing the service account authentication to fail.