@Smalyshev adding you in the off chance this is in any way related to the reindexing.

I can add Lexeme values to https://www.wikidata.org/wiki/Q4115189 just fine... Also, I do not believe this would be related to indexing.

I tried it on https://www.wikidata.org/wiki/Lexeme:L666 and I get the input field

Ok this is really weird. Some people on IRC have the issue and some not. Different code on different servers?

What version do you see on https://www.wikidata.org/wiki/Special:Version

I see

1.32.0-wmf.5 (rMWfda06ee2e1ff)
14:24, 23 May 2018

I also see

MediaWiki 1.32.0-wmf.5 (rMWfda06ee2e1ff)
14:24, 23 May 2018

I'm using mw1267 as a server and for me Special:Version says 0.0.0 (4ec186e) 22 mei 2018 14:24 (for Lexeme)

For me:
1.32.0-wmf.5 (rMWfda06ee2e1ff)
16:24, 23 May 2018

@Mbch331: I'm also getting the same for WikibaseLexeme. That is the current deployed version.

@mmodell And I'm Special:Version gives the same version for MediaWiki as Lydia and you.

We are definitely running the same version of the code everywhere, it must be something else causing the inconsistent results.

Thank you for checking!

New occurence spotted? https://www.wikidata.org/wiki/Wikidata_talk:Lexicographical_data#%22Handling_of_values_for_%22wikibase-form%22_data_type_is_not_yet_supported.%22

So, this seems to somehow be tied to user sessions / cookies.
We just fixed an occurrence for a user by removing their cookies.
If your experiencing this issue try deleting your cookies (logging out and back in might be enough) and report back.

Ok I deleted my cookies and that seems to have fixed it. Logging out and in again wasn't enough.
Thanks so much for investigating! Let's close this tomorrow if we don't hear more.

It worked for Micru as well after deleting cookies.

Found an affected client that carried a local storage entry MediaWikiModuleStore:wikidatawiki with a huge map of items. Removing this entry and reloading the page resolved the issue.
https://www.mediawiki.org/wiki/ResourceLoader/Features#Store

We probably need so way of cleaning such caches when we update. Otherwise these things will keep happening. Maybe some kind of version counter and some code on JS side that would clean all local storage if version is wrong?

In T195402#4229354, @Pablo-WMDE wrote:

Found an affected client that carried a local storage entry MediaWikiModuleStore:wikidatawiki with a huge map of items. Removing this entry and reloading the page resolved the issue.
https://www.mediawiki.org/wiki/ResourceLoader/Features#Store

i just ran into an issue with this again while a data type id was changed, i wonder if we should come up with a "real" solution to this rather than telling users to clear their local storage

@Addshore No doubt about it. I did not want to create the impression that I consider it a valid approach to put that burden onto the end user (professional honor & UX-wise).

@Addshore The thing seems to happen again with Senses. Some users ran into a "Handling of "wikibase-entityid" values is not yet supported." error message while adding the translation statement to a Sense.

In T195402#4228553, @Addshore wrote:

So, this seems to somehow be tied to user sessions / cookies.
We just fixed an occurrence for a user by removing their cookies.
If your experiencing this issue try deleting your cookies (logging out and back in might be enough) and report back.

^^ same fix applies