client sent header field with too long length value while processing HTTP/2 connection

[andreios]

"client sent header field with too long length value while processing HTTP/2
connection"

I get this error message in conjunction with nextcloud client. The client 
displays this: "error transferring /path/to/file/".

Couldn't find much information about this or a valid answer with google.
Mostly it is suggested to raise one or more of:
fastcgi_buffer_size, fastcgi_buffers, fastcgi_busy_buffers_size,
http2_max_header_size, http2_max_field_size. 

I have tried all of that. Nothing changed, even with very high values.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,286817,286817#msg-286817