I had a problem on a Windows Server with a fresh installed Icinga2 Agent (2.13.1).
Only the “check_load” command produced this output (german): “Die angegebene Sprachenkennung f³r die Ressourcen wurde nicht in der Image-Datei gefunden.”
After some investigation I was sure that this was not a problem with the character encoding on this system or with the Icinga2 Agent.
I was able to fix this problem by a “manual rebuild” of the performance counters.
Manually rebuild performance counters for Windows Server
This worked for me:
cd c:\windows\system32 lodctr /R cd c:\windows\sysWOW64 lodctr /R WINMGMT.EXE /RESYNCPERF