J2CA0045E: Connection not available while invoking method createOrWaitForConnection for resource jdbc/xx solution

The reason this error is coming is lack of connection pool to create connections.

Solution:

Increase the maximum connection pool size .If you are increasing the connection pool size at cluster scope remember use the below logic to set.

maxpoolsize * number of cluster members should not be greater than connection setting in database.
If above solution does not resolve then enable database trace to analyse further the PoolManager.