Hi @texnixe , @scma!
So I just installed the starterkit, and I run in the same problem, so I can visit the website, I can access the panel, but when I try to change any text field it opens the same error page
{"status":"error","message":"Unauthenticated","code":401,"exception":"Kirby\\Exception\\AuthException","key":"error.auth","file":"..\/public_html\/test-kirby\/kirby\/config\/api\/authentication.php","line":14,"details":[],"route":"(.*)\/lock"}
thank you!
Hi!
I am here with an update 
I contacted my hosting provider and they found that it was caused by ModSecurity. On their newer servers, stricter security rules were in place, which led to a 406 Not Acceptable error. After they disabled ModSecurity for my domain, the issue was resolved 
Hope this can help others!
I’m having a similar issue, but with fewer details. It’s also not likely my host, as my other Kirby CMS site on the same host has no issue
{"status":"error","message":"Unauthenticated","code":401,"key":"error.auth","details":[]}
Edit: It was my host, they also migrated my server and enabled a CDN with a security level that essentially saw most IPs as a threat. At first there was some confusion, because when the customer support attempted to save something, it worked. Which in the end makes sense, as their IP was just not perceived as a threat.