Call to undefined function xmlsitemap_get_priority()

I checked the code, and there aren't any references to that function. For the reason of the error you are seeing, I can only think that maybe you have a mix of old, and new files.

I will investigate this.

For the second part of the report, I found an error in the code; I am opening a different issue report for that.

See #458132: xmlsitemap_output() references a not initialized variable for the other report.

The sitemap cache is generated only when the anonymous user access the sitemap; if you see it as authenticated user (in other words, if you are logged in), the sitemap could not be updated, or you could get a 404 error message.

I am changing the category of this report because the code doesn't contain any reference to xmlsitemap_get_priority(); the code contained a reference to that function, but it has been fixed (see #456288: xmlsitemap_get_priority() is not defined).

I am changing the status of the report.

Also I'm a little bit irritated: do I have to create the xmlsitemap-directory manually?
There wasn't any available in sites/default/files/

The directory is created from the code, if it doesn't exist already, in the moment it needs it; this usually happens one instant before the cache files are created.

I am setting this report as fixed.