Crawl errors and hreflang

using hreflang

[Prasawet]

For my site: example.com I build subdomains de.example.com and es.example.com (within same name folders in the root).

So, the page example.com/test have this in meta:

<link rel="alternate" hreflang="en" href="http://example.com/test" />
<link rel="alternate" hreflang="de" href="http://de.example.com/testen" />
<link rel="alternate" hreflang="es" href="http://es.example.com/pruebas" />

In GWT (for main domain) under CrawlErrors/Not found I see:
URL: http://example.com/de.example.com/testen
linked from: http://example.com/test.
...and so on for almost every link used with link rel="alternate".

It seems that Google completely misunderstood link rel="alternate" even it is built by his rules...or I did something wrong.

[lucy24]

If all your links, everywhere, start with protocol-plus-domain, then you have done it right and google needs to go kick their computer. It's got nothing to do with rel="alternate" or anything else that might accompany the link.

It's worth double-checking your code, though.

:: detour to double-check ::

Their own examples [support.google.com] begin with full protocol-plus-hostname, so it's no use arguing that the format is meant for links on the same host.

[not2easy]

Another Google support page give more information about usage including the hreflang="x" tag that might be useful: [support.google.com...] especially if there is any auto-redirecting going on.

[Prasawet]

@lucy24
Yes, I did do the double-check a couple times and everything is like I mentioned, quite distrbing.

@not2easy
I checked all G. pages about this issue. Anyway, I don't have auto-redirecting system, just a

link rel="alternate"

part to inform SE about another point of view.

Thank you all for your contributions