Google Maps will not load KML layer from my site

Question

I have a site that contains kml. The kml is shown as a layer in Google Maps. The maps are on the same site. Until recently (may 12th), this worked fine, but now it stopped working. The kml itself is OK, it can be used in Google Earth. When I copy the kml to another site I can load it in Google Maps without any problem. Is it possible that my site is on a "blacklist" for some reason? Traffic is low. I did not use an API key. I do now but that did not solve the problem.

You can see the difference here:
1 - with kml from my site
2 - with kml placed elsewhere
The first one fails, the second one works. The kml placed elsewhere is an exact copy of the kml from my site. The kml from my site is served with media-type application/vnd.google-earth.kml+xml. It is dynamically generated.

Answer 1

In my case i got FETCH_ERROR on kml status-

Because my site allow only tls 1.2 secure connection.

When i put the files on another server- it's work.

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Update 1-

It happend again after sometime, this time use the same domain helped.

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Update 2-

Now it happened to me because of uppercase letters... If it happens to you -

So - make sure that the link you put has uppercase and lowercase letters in the KML file just like in the file on the server...