Problem after updating "lost connection to api"

Please follow the below template, it will help us to help you!

I had been running an oldish version of pihole and today I noticed that V4 was available. So I upgraded using pihole -up and everything seemed to go fine. However, later I noticed that my web interface no longer displays graphs.

I've tried the following:

  • I restarted ftl.
  • I cleared my browser's cache.
  • I upgraded the OS on my pi to the latest version.
  • I uninstalled pihole and reinstalled from the command line.
  • I've rebooted my pi in between lots of these changes.

I searched for similar problems but the don't seem to be exactly this, even though the text error message is identical.

The previous version I was running (about May 2018 time frame) worked with no problems.

Expected Behaviour:

on the web interface dashboard I expect to see graphs

Actual Behaviour:

I see spinning arrows instead of graphs and "lost connection to api" at the top of the page.

Debug Token:

kxtub8y8ka