We receive an email from Salesforce saying
Every waiting flow interview has an associated user — the person who caused the interview to start waiting. If that user is inactive, the interviews can't resume.John Doe (005xxxxxxxxxxxx) is inactive, so please delete the following flow interviews.
Without thinking too much I went straight away to the Process Builder to check if it uses hardcode Id referring to the inactive user and I found none. The process builder is fine.
The email was sent is to inform us that there some process builder on the waiting list and not able to get fired because it was created by an inactive user.
The user left the company for quite some time, how is possible for him to fire the process builder?
What is Paused and Waiting Interview?
Paused and Waiting interview only applies on schedule action process builder or time-dependent action. You can check Paused and Waiting Interview at Setup | Create | Workflows & Approvals | Flows and look at Paused and Waiting Interview section.
Why I receive the email above?
Because the process builder has Scheduled action to send an email alert on 15 days before Close Date. Let's say the Close Date is in next year and the process builder is fired this year.
The action to send email will be listed in Paused and Waiting Interview. However, Salesforce will remove this interview from waiting list after it tried to execute once. I noticed that because when I clicked the link that provided in the email after investigation and the link is no longer available.
Data Not AvailableThe data you were trying to access could not be found. It may be due to another user deleting the data or a system error. If you know the data is not deleted but cannot access it, please look at our support page.
The email just to warn us in case we got many more interview in pending that owned by the user.
What will happen if we deploy a new version of Process Builder while some of the previous version in pending list?
Any deactivated version Process Builder will continue as usual and Salesforce will not allow us to delete this version. Refer to link here. If we think the previous version should not run then we should go and delete the waiting list.