Builder app unable to build: "error checking docker containers"

I am unable to deploy via fly deploy since Saturday morning due to

Error: failed to fetch an image or build from source: error building: failed to receive status: rpc error: code = Unavailable desc = error reading from server: EOF

When I check the logs of the ly-created builder app (fly-builder-cool-silence-2129), I see constantly growing log repeating the following two lines:

2023-08-28T08:27:47.109 app[2874533c052658] ams [info] time=“2023-08-28T08:27:47.108699984Z” level=debug msg=“checking docker activity”

2023-08-28T08:27:47.109 app[2874533c052658] ams [info] time=“2023-08-28T08:27:47.108890469Z” level=warning msg=“error checking docker containers”

This has been going on for some 20 hours now so it does not look like a temporary system hiccup, and there are no problems reported at Sign In · Fly .

What could be going on? When can I do? Thanks for any tips!

(I see there was a similar problem year ago Error failed to fetch an image or build from source: error connecting to docker: remote builder app unavailable, without any resolution but with the suggestions that it could be something with European regions)

Destroying the builder app helped. The next deploy created a new one, which is working fine.