XAPI Service unable to start , error : xapi dies but pid file exists.

XAPI Service unable to start. It shows that the it already has a pid and is dead. Looking at the logs xensource.log, you will find INTERNALERROR as below: xapi top-level caught exception: INTERNALERROR: Xmlm.MakeStringBuffer.Error, -372779099 Caught exception at toplevel:...