Cannot Verify Server ID for random Spam domain

I was about to grumpily reply and say "no, it's not a calendar issue" — but, actually, I think it is/was. A very clever one. As far as I can tell — since the notifications have now ceased — it was the innocent-looking "Events" calendar that I've circled which was causing the irritating pop-ups. Removing it has, so far, removed them.

Thanks very, very much for the help — and I hope this post might help others with the same issue in future.

Following up on last comment, I’ve completely reset my phone and that message still comes up. When you click details there’s no discernible way to see where it’s coming from (if it’s connect to an app or if it’s spyware).

Hello calamityjenntx,

Thank you for using Apple Support Communities. We understand that you're seeing an alert about an unfamiliar server when using your iPhone. We're happy to look into this with you.

Let's make sure that you don't have any spam calendars on your iPhone. Please use the steps in the resource below:

Delete spam calendars and events on iPhone

Let us know the results. Be sure to include additional error messages and any other troubleshooting steps that you may have tried.

Have a nice day!

Good that you got it.

When the subscribed calendar is working…

Those event notifications are usually offered by mail or by website.

The events (if you scroll down) also identify the calendar.

When in doubt, match the subscribed calendar colors with the event colors.

Was the calendar spam from a plum-purple-ish color, matching that from your image? If so, that’s your target.

Whatever the subscribed calendar name that might be shown.

When the subscribed calendar domain server identity checks are failing (as has been mentioned in this thread), then there’s rather less to go on; the calendar alert colors aren’t shown. (I don’t know what shows with the “details” beyond the cert, and which isn’t really all that useful for seeing what fetch triggered the failure without also rummaging the ℹ️ buttons in each the subscriptions, and which is all entirely non-obvious.)

I’m having the same problem. It’s not a calendar issue/pop up. It looks like it’s some sort of malware. I think it actually was responsible for wiping half my contacts list.

Exactly the same situation for me, across two linked iPhones of different vintages. It's definitely not a calendar issue, and seems certain to be malware. Please can Apple advise an appropriate solution?

ripamel wrote:

Exactly the same situation for me, across two linked iPhones of different vintages. It's definitely not a calendar issue, and seems certain to be malware. Please can Apple advise an appropriate solution?

This looks like a subscribed spam calendar that’s failing to pass checks.

Please verify that you have no (unexpected) subscribed calendars.

… Delete spam calendars and events on iPhone - Apple Support

Thanks!! This helped me a lot.

There were two "Event" calendars hidden in my calendar list

I'm afraid I can't answer, as I just took the time-saving decision to delete that entire calendar!