What is the "Uncategorized" Android Notification Channel and when does it appear?

Question

When switching the application to Android O, I noticed a strange thing. Sometimes my foreground service notification goes to a channel that I haven't done yet, called Uncategorized. I have no idea how and when this happens.

Channels are always created before notifications are sent, and the channel ID is correct. I tried putting a random string as the channel identifier to see if I can reproduce the problem, but the notification just does not appear in this case. So this seems like a strange case when a channel has already been created before.

This is the channel page:

And this is the channel that appears in the list of all channels of the application (note that I deleted the icon for privacy reasons).

Does anyone have experience with this and could they explain when this can happen? Unfortunately, I did not find any documentation about this and did not hear anything about it in the Google I / O negotiations.

Answer 1

I think this happens if part of your application does not support the notification channel.

In particular, in our case, if the SDK of our channel is a notification channel, but the application is aimed at 25 and uses outdated functions. We will always notify an outdated application for this channel without a heading.

I can imagine that there are other cases when the OS decides that you need this channel, because the OS thinks that not everything is correctly ported. Do you have targetSDK of 26 for the whole application with forced support of 26.0.1?