I also get the Internal Server Error when viewing the IP address Blocklist Logs.
On IPFire 2.27 (x86_64) - Core-Update 170 Development Build: master/ef7d41ef
EDIT: Here is the /var/log/httpd/error_log:
[Mon Aug 15 15:58:50.737978 2022] [cgid:error] [pid 28150:tid 132901295343168] [client 192.168.6.100:56287] End of script output before headers: pakfire.cgi, referer: https://192.168.6.1:444/
[Mon Aug 15 16:01:14.481090 2022] [mpm_event:notice] [pid 28145:tid 132901568751488] AH00491: caught SIGTERM, shutting down
[Mon Aug 15 16:03:09.854464 2022] [mpm_event:notice] [pid 2678:tid 140426358073216] AH00489: Apache/2.4.54 (Unix) OpenSSL/1.1.1q configured -- resuming normal operations
[Mon Aug 15 16:03:09.855460 2022] [core:notice] [pid 2678:tid 140426358073216] AH00094: Command line: '/usr/sbin/httpd'
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to read file /var/ipfire/ipblocklist/settings at /var/ipfire/general-functions.pl line 219.
[Mon Aug 15 16:41:01.150152 2022] [cgid:error] [pid 2683:tid 140425700570688] [client 192.168.6.100:62625] End of script output before headers: ipblocklists.dat
Unable to read file /var/ipfire/ipblocklist/settings at /var/ipfire/general-functions.pl line 219.
[Mon Aug 15 16:41:04.833062 2022] [cgid:error] [pid 2683:tid 140425692177984] [client 192.168.6.100:62641] End of script output before headers: ipblocklists.dat
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to read file /var/ipfire/ipblocklist/settings at /var/ipfire/general-functions.pl line 219.
[Mon Aug 15 16:47:07.151073 2022] [cgid:error] [pid 2683:tid 140426069653056] [client 192.168.6.100:63515] End of script output before headers: ipblocklists.dat
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to write file /var/ipfire/ipblocklist/modified at /var/ipfire/general-functions.pl line 256.
Unable to read file /var/ipfire/ipblocklist/settings at /var/ipfire/general-functions.pl line 219.
[Mon Aug 15 17:36:09.184656 2022] [cgid:error] [pid 2683:tid 140425692177984] [client 192.168.6.100:54705] End of script output before headers: ipblocklists.dat, referer: https://192.168.6.1:444/
I can confirm that that fixes the problem and also that on a fresh install that directory is owned by nobody:nobody.
In the update.sh file for the upgrade to CU170 it has the chown nobody:nobody command for the directory /var/lib/ipblocklist/ but not for the directory /var/ipfire/ipblocklist/
@siosios will you do an update to the bug report for this. Your IPFire people email address and password credentials will work on the IPFire Bugzilla.