Characters such as ä or ö don't work

OS Name/Version: Windows 10 Pro

Product Name/Version: v2.3.2.4, built 22/02/2022 10:57

Problem Description: Can’t use special characters in my Minecraft server commands such as ä or ö, the just show up as A¤

Steps to reproduce:

  1. Send command that has ä or ö.
  2. Get A¤

Actions taken to resolve so far: Tried to Google this, but no result. I really don’t know where to start.

unable to reproduce

you need to have your system locale not be english, for this to break. This is obviously a failed conversion between UTF-8 and ISO-8859-xx.
This also shows, that the HTTP-Server ignores the provided Character-Encoding of the HTTP-Request.

Have checked. AMP is UTF-8. Searching in discord returned the following:

Well … that apparently means, that Java is parsing the stream using the System-Charset and not UTF-8 (and the System is not configured to use UTF-8 as the default encoding. e.g. Windows, which simply doesn’t support that setting.)
That would mean, you need to either force java to use UTF-8 as the system encoding, or AMP needs to convert its UTF-8 to the System-Encoding before sending it to Java (Minecraft)