Some server nodes portal is not starting after restart

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Symptom
After restart of cluster Environment, on some of the server nodes the Portal is not coming up.
On the screen you can see sometimes the following message:
“Application error occurred during request processing.
Details: java.lang.NullPointerException: null”
The defaultTrce files could show a varios of traces like:
java.sql.SQLException: Datasource name not found: Object not found in lookup of EP_PCD.
Other [...]