The user created a Flow in Flow Designer which was working fine for months in their lower instances (sub-Production). The user tried checking to ensure all references and actions were current/relevant, and they were. Once the user clicked the "Activate" the Flow, even though they received a notification that the Flow activated, the Flow does not actually get activated, and an "Internal Server Error" error is thrown with no other details.
This behavior was due to PRB1420275.
After speaking with ServiceNow Developers, it was found that, as stated above, the root of the issue was due to PRB1420275.
The issue, as the PRB describes it, is that users cannot insert tables into the email editor in Flow Designer without getting a internal server error. If the email HTML body contains a table with data pills, while publishing/activating the flow, an internal server error will be seen.
Additionally, the below error was seen in the logs:
Flow Designer: Failed to invoke public com.glide.flow.model.ComponentInstance() with no args
The workaround for this PRB is to delete the "Send Email" actions within the Flow and recreate them.
Unfortunately, there will not be a more robust solution until beyond the Quebec family release.