Custom header plugin not working with OJS 3.3.0.12

Hi all

The newest release here Releases · pkp/customHeader · GitHub is not working with our OJS 3.3.0.12 version. Is it theoretical compatible? In the backend I get a “Failed Ajax request or invalid JSON returned” error when I try to click “settings”.
The apache error_log looks like this:


[Tue Oct 11 14:33:25.625182 2022] [proxy_fcgi:error] [pid 296523] [client 130.92.165.70:64349] AH01067: Failed to read FastCGI header, referer: https://bop.unibe.ch/SJM/management/settings/website
[Tue Oct 11 14:33:25.625212 2022] [proxy_fcgi:error] [pid 296523] (104)Connection reset by peer: [client 130.92.165.70:64349] AH01075: Error dispatching request to : , referer: https://bop.unibe.ch/SJM/management/settings/website
[Tue Oct 11 14:33:48.917159 2022] [proxy_fcgi:error] [pid 296522] [client 130.92.165.70:64352] AH01067: Failed to read FastCGI header, referer: https://bop.unibe.ch/SJM/management/settings/website
[Tue Oct 11 14:33:48.917185 2022] [proxy_fcgi:error] [pid 296522] (104)Connection reset by peer: [client 130.92.165.70:64352] AH01075: Error dispatching request to : , referer: https://bop.unibe.ch/SJM/management/settings/website

Thanks
Jan