hreflang tags use invalid language or region codes

hreflang is a tag used on multi-language or multi-country sites to tell search engines which page version to show visitors from a given country or speaking a given language. Valid values follow a standard format called BCP-47, such as en or en-AU. This check found one or more hreflang values on this site that are not valid codes in that format. Search engines simply ignore hreflang values they cannot parse, which means the invalid entries provide no benefit at all, and visitors can end up served the wrong country or language version of a page as a result, undermining the reason for setting up hreflang in the first place. Your developer should correct each invalid hreflang value to a proper language code, like en, or language-region code, like en-AU or fr-CA. This is a text correction in the page's code or CMS settings, usually finished within an hour once the invalid values are listed.