Issue
You are attempting to run a database maintenance or perform a database upgrade and you get the following message:
Maintenances are disabled at this time
Resolution
Heroku might need to temporarily disable maintenances on Heroku Postgres databases and other data add-ons for a short period of time. This can happen when our engineers are investigating potential platform issues, due to an ongoing platform incident, or due to maintenance being performed on the platform.
If you see the Maintenances are disabled at this time message, check the Salesforce Trust page for context and wait before performing the upgrade/maintenance again. Typically maintenances are disabled for less than 24 hours.