Database Error: remaining connection slots are reserved for non-replication superuser connections

[canumula]

This error usually occurs when the database reaches the maximum number of connections allowed based on the compute add-on.

To overcome this, the connections need to be optimized as mentioned here: https://supabase.com/docs/guides/platform/performance#optimizing-the-number-of-connections

Additionally, you can try using the connection pool to help solve this issue:
https://supabase.com/docs/guides/database/connecting-to-postgres#connection-pooler

If you're already using connection pooling and still hitting the maximum connections, then it is suggested to upgrade your compute add-on that allows more connections: https://supabase.com/docs/guides/platform/compute-add-ons

[TheOtherBrian1]

You can inspect your database’s connections with Supabase's Grafana Dashboard.
There is a GitHub repo that outlines the process for setting one up locally or on Fly.io for free.