1 of 1 people found this helpful
Which version of Notifications and AF Server are you using? We have documentation for this error message with Notifications 2012 in KB00972, which lists several solutions depending on your setup.
Let me know if you're able to resolve your issue using that KB or whether you need further assistance.
This is a pretty common issue and you can find different potential solutions in this KB: https://techsupport.osisoft.com/Troubleshooting/KB/KB00972/
Is this a new install? If it is, why not install the newer PI Notifications rather than the legacy Notifications?