Thank you for the notice, @jeblad. I'll follow up on the Torget.

As I could not identify any problems with the gadgets (sure there are problem with them) I suspect there are something interfering from other user settings. Trying to add and remove each of them will take a lot of time.

I also suspected the CodeMirror extension, but to no avail. Also I tested without the beta functions, but nothing found.

Thank you very much for the time you spend to help others!

In T178191#3687666, @jeblad wrote:

Trying to add and remove each of them will take a lot of time.

I think &safemode=1, described here, will help you to save a lot of time next time!

A stack trace from the user

TypeError: Cannot use 'in' operator to search for 'length' in ["en"]nb,hu,fr,de,nl,no,nn,en,sv,se
    at isArrayLike  (…)
    at Function.each (…)
    at Object.mw.ime.getIMELanguageList (<anonymous>:118:11274)
    at Object.mw.ime.addIme (<anonymous>:122:549)
    at Object.mw.ime.handleFocus (<anonymous>:122:456)
    at HTMLInputElement.<anonymous> (<anonymous>:122:1)

Seems like the debug was lost, but perhaps the functions can be located.

Note that getIMELanguageList is not present in in the GitHub repo, so it is probably added by code reusing the jquery.ime

This sounds like @Amire80 or @KartikMistry …

Found it in ULS, but it is not clear to me why it breaks. Perhaps something is wrong with the structures it uses.

Hmm, adding ULS tag.

Both Chrome and Firefox? Important: latest versions of Chrome and Firefox?

I can ask for specific browser versions, but the user avilena says "I have tried with the latest version of Chrome and Firefox, 64-bit." ("Jeg har prøvd med siste versjon av Chrome og Firefox, 64-bit.")

OS: Windows 10 Home, Chrome: 62.0.3202.62. The user has tried several browser versions.

Only fix seems to be to turn off IME in ULS, and as the user does not use this it has no consequences.

The problem does not seem to be associated with any specific IME, the only solution is to turn it off completely.

I can not reproduce this in versjon 61.0.3163.100 (Offisiell delversjon) Built on Ubuntu , running on Ubuntu 17.04 (64-bit)

There is a gadget "Språkrekkefølge: Sorter lenker til andre språk akkurat slik du ønsker det. Se bruksanvisning." that might interfere with languages. It is the last one in the section "Innhold". Code at w:no:MediaWiki:Gadget-InterwikiOrder.js The user that has the problem has disabled all gadgets, so I doubt this is the root cause.

Another common bug is setting language "no" vs "nb" at "internasjonalisering" on w:no:Special:Preferences#mw-prefsection-personal