ORA-04061: existing state of package body “XXXX” has been invalidated

[WF_ERROR] ERROR_MESSAGE=3835: Error '-20002 - ORA-20002: 2018: Unable to generate the notification XML. Caused by: 2020: Error when getting notification content. Caused by: ORA-04061: existing state of  has been invalidated

ORA-04061: existing state of package body "APPS.XX_CHANGE_REQUEST_PKG" has been invalidated

ORA-04065: not executed, altered or dropped package body "APPS.XXI_CHANGE_REQUEST_PKG"

ORA-06508: PL/SQL: could not find program unit being called: "APPS.XX_CHANGE_REQUEST_PKG"

Wf_Notification.GetAttrClob(2836675, XX_NOTIFICAT' encountered during execution of Generate function 'WF_XML.Generate' for event 'oracle.apps.wf.notification.send'. ERROR_STACK=

WF_MAIL.GetLOBMessage3(2836675, PRDMAIL, 2020: Error when getting notification content. Caused by: ORA-04061: existing state of  has been invalidated

ORA-04061: existing state of package body "APPS.XX_CHANGE_REQUEST_PKG" has been invalidated

ORA-04065: not executed, altered or dropped package body "APPS.XX_CHANGE_REQUEST_PKG"

ORA-06508: PL/SQL: could not find program unit being called: "APPS.XX_CHANGE_REQUEST_PKG"

Wf_Notification.GetAttrClob(2836675, XX_NOTIFICATION_MESSAGE, text/html)

Wf_Notification.oldGetAttrClob(2836675, XX_NOTIFICATION_MESSAGE, text/html)

WF_NOTIFICATION.GetFullBody(nid => 2836675, disptype => text/html)

WF_MAIL.GetLOBMessage3(nid => 2836675, r_ntf_pref => MAILHTML), Step -> Getting text/html body)

WF_XML.GenerateDoc(oracle.apps.wf.notification.send, 2836675)

WF_XML.Generate(oracle.apps.wf.notification.send, 2836675)

WF_XML.Generate(oracle.apps.wf.notification.send, 2836675)

Wf_Event.setMessage(oracle.apps.wf.notification.send, 2836675, WF_XML.Generate)

Wf_Event.dispatch_internal()

--For the above issue the below solution worked for us.

A bounce of Workflow and Mailer Services

The below reference helped

http://ioraclefusion.wordpress.com/2010/03/22/ora-04061-existing-state-of-package-body-xxxx-has-been-invalidated/