All dashboards showing 'No data' after upgrading

I upgraded from 7.x to 9.5.7 (docker image) and now all my dashboards, regardless of data source (prometheus, graphite, cloudwatch), show ‘no data’ for all panels regardless of timeframe.

I can check the data sources and it says the test connection succeeds and nothing has changed for any of the data sources. I can’t find any errors in the docker container logs, in the ui, or in the web browser console. If I ‘Explore’ on the dashboards, I get “Method not allowed” in the Grafana UI but that’s all. Everything is there, but nothing is working.

Anyone know how I can go about debugging this?

Once it happened to me something like that.

I deleted all my data sources and create them again (entered the exact same values). and it worked!
clarification: by delete I mean in the Grafana settings under data sources… (Do not delete your actual data sources…)

also, double check that you did not replace some custom configuration files, and that you ran the command to upgrade plugins.