If I turn off in the configuration \Add the suffix to the URL\ then is ok.

any ideas?

any ideas?

yes report to the author of your Joomla template ...
and ask them to fix
or if they are no longer updating the template / framework you can try to patch it your self

if you enable Joomla debug and you try to load url
e.g.
domainname.pl/index.xml

you will see that (quite propably) the call addFavicon() is happening by custom code in your Joomla template that does not check if the current request was for an HTML page

Hi

I enabled Joomla debug in Global Configuration - System and Debug System is ON
I enabled reporting errors to development mode

if I load url domainname.pl/index.xml have no any debug .
Just message Error: Call to undefined method Joomla\CMS\Document\XmlDocument::addFavicon(): View not found [name, type, prefix]: article, xml, contentView

this error is under Helix3 template and template is up to date . I have few websites based on Helix3 but just on this one is the problem.

I checked Protostar and Beez3 template with link domainname.pl/index.xml
I have also no debug there, and error message is Error: Call to undefined method Joomla\CMS\Document\XmlDocument::addHeadLink(): View not found [name, type, prefix]: article, xml, contentView - little different error but is giving 404

If i turn set Add Suffix to URL to OFF then everything is working perfect.

and even I disable all modules have still problem

Please use the forum for support

HTTPS://forum.joomla.org

Or

http://forum.joomla.pl

I checked Protostar and Beez3 template with link domainname.pl/index.xml
I have also no debug there, and error message is Error: Call to undefined method Joomla\CMS\Document\XmlDocument::addHeadLink(): View not found [name, type, prefix]: article, xml, contentView - little different error but is giving 404

Yes but the above error is a different issue

• that is caused by including the search module without making sure that current JDocument is an JDocumentHTML
• for which we have a PR already

Regarding error of this issue

... addFavicon()

From a quick search the above will not happen with Protostar and Beez3 templates because they do not call addFavicon() directly, instead the loading of it happens by JDocumentHTML::_loadtemplate,

but several template framework will load their template files with custom code and they will call addFavicon() manually !

and if they do not check the current format is HTML (which means that the JDocument is an JDocumentHTML)
then when they call addFavicon() they will get this error because addFavicon() only exists in JDocumentHTML.

This is not a bug that can be fixed in the core unless Joomla starts adding empty methods in classes for the sake of avoiding such errors

If I turn off website in global configuration and tyr to login on front than link domainname.pl/index.xml redirect to domainname.pl/index.php and do not have errors. Strenge