Could be a ghost process keeping that port bound? Or some other new program that was just introduced and coincidentally also uses that port?
Either way, if the port is in use than you should be able to find out from where using the command: netstat -a -b
And then there is always this problem solver which is around since the dawn of the personal computer: have you tried turning it off and on again?
If you have JDBC steps involved then it might be that your JDBC connection pool is too small.
Unfortunately, right now, I cannot locate the property name with which you can increase that pool. Maybe another community member has that piece of info readily available?