It looks like wbRepo is misconfigured:

» mw.config.get('wbRepo').url
← "https://www.wikidata.org"

This causes the entity selector (and probably other things as well) to use the wrong API URL.

Change 471000 had a related patch set uploaded (by Addshore; owner: Addshore):
[operations/mediawiki-config@master] List wikidataclient-test in CS.php dblists

https://gerrit.wikimedia.org/r/471000

Change 471000 merged by jenkins-bot:
[operations/mediawiki-config@master] List wikidataclient-test in CS.php dblists

https://gerrit.wikimedia.org/r/471000

Mentioned in SAL (#wikimedia-operations) [2018-11-01T12:50:35Z] <addshore@deploy1001> Synchronized wmf-config/CommonSettings.php: List wikidataclient-test in CS.php dblists T208488 (duration: 00m 57s)

In T208488#4712560, @Addshore wrote:

This appears to be fixed now.
But some bad values might be cached in resource loader for a little while.

How long? Seems to still not work.

test.wikidata.org gets updated to a new MediaWiki version today 20:00 – 22:00 UTC, I hope that’ll resolve the issue. Otherwise we’ll have to revisit this issue.

In T208488#4723829, @Lucas_Werkmeister_WMDE wrote:

test.wikidata.org gets updated to a new MediaWiki version today 20:00 – 22:00 UTC, I hope that’ll resolve the issue. Otherwise we’ll have to revisit this issue.

Ah okay, thanks :)

Hm, I’m still able to edit (I tried force-reloading the page too).

In T208488#4997988, @Lucas_Werkmeister_WMDE wrote:

Hm, I’m still able to edit (I tried force-reloading the page too).

I get "Could not save due to an error.
Revision with ID not found." Even with forced reloading.

Anyways, it’s probably better to open a new task. Can you do that and then we’ll continue debugging there?