Adding more pages to [[ https://incubator.wikimedia.org/wiki/Wp/cnr/Po%C4%8Detna_stranica | Montenegrin Wikipedia ]] (in the incubator) is impossible due to the error: "You are trying to create a page without a valid ISO 639-1 or -3 code..." (screenshots)
Montenegrin language has a valid ISO 639-3 code, check [https://en.wikipedia.org/wiki/ISO_639:c here] or [https://iso639-3.sil.org/code_tables/639/data/c here]. It is completely in line with[[ https://incubator.wikimedia.org/wiki/Incubator:ISO_639 | the requirements ]].
Also, there are already 1,968 articles with wp/cnr prefix.
It is possible to edit existing pages, but not to add a new one.
On the [[Talk:Wp/cnr/Početna_stranica|cnr talk]] page, other users were complaining about being unable to create new pages (a few last posts), and this has been happening for at least a year.
**To replicate**
Try adding a page on https://incubator.wikimedia.org/wiki/Wp/cnr (with a new user?)
**Test cases (all on Ubuntu 20.04.3)**
1. FF and my usual Wiki user
{F36861538}
2. Chrome and new Wiki account
{F36861540}
3. Brave without login
{F36861542}
**Related posts**
https://incubator.wikimedia.org/wiki/Incubator:Administrators%27_noticeboard#Unable_to_create_Wp/cnr/_page
https://incubator.wikimedia.org/wiki/Incubator:Community_Portal#Unable_to_create_Wp/cnr/_page