What is this?

Some time ago, I got this message when executing a Custom Connector from a Logic App. The response was very strange, and was returned in that object way that an HTTP action sometimes does:

{
'content-type': 'application/octet-stream',
'content': 'eyJjb2RlIjogIkFwaURpc2FibGVkIiwgIm1lc3NhZ2UiOiAiQVBJIGhhcyBiZWVuIGRpc2FibGVkIGR1ZSB0byBpbmFjdGl2aXR5LiBQbGVhc2UgdXBkYXRlIHRoZSBDdXN0b20gQ29ubmVjdG9yIHRvIGVuYWJsZSBpdCBhZ2Fpbi4ifQ=='
}

Running the \$content thing thru a Base64 decoder I got back:

{'code': 'ApiDisabled', 'message': 'API has been disabled due to inactivity. Please update the Custom Connector to enable it again.'}

The connector had been … disabled?!!!
Does this seem familiar?

What to do (short term)

The very short version is to update the connector. To basically force Azure to deploy it again. To solve this I simply added a space in the description-field and clicked Update Connector. Done.

Why did this happen?

I raised a ticket with MS Support and got a very clear answer: They used to disable connectors that had not been used for 30 days. Why? They did not say, only that they no longer have that policy. I think it was due to the datacenter being close to overloaded (thanks Covid-19) and they wanted to remove unused resources.

What to do (long term)

You need to look at your connectors and find all those that have not been used for a while. The Enfo support team checked the run history of all Logic Apps that uses Custom Connectors. If a Logic App had not been run for a long time, they updated the connector behind it. I think you should do this as well.
In our case it was easy, two Logic Apps had not been run for two months and all others are running on a daily basis.