[Koha] Koha 21.05 Internal server error on https

[Jacopo]

Hi,
I recently tried to install Koha 21.05 on a Debian 10.10 server and then 
to move 2 libraries from another Koha instance (20.05), which was 
unsuccessful but will be the subject of another email. Currently I am 
experiencing a different issue: recurrent internal server errors both on 
for the opac and the intranet when connecting though https (http is 
working).

The error I get, from /var/log/koha/library/opac-error.log:

```
[Thu Sep 23 14:36:17.087937 2021] [cgi:error] [pid 21969] [client xxx] 
AH01215: Use of uninitialized value $compiled in concatenation (.) or 
string at /usr/lib/x86_64-linux-gnu/perl5/5.28/Template/Provider.pm line 
572.: /usr/share/koha/opac/cgi-bin/opac/opac-main.pl
[Thu Sep 23 14:36:17.088568 2021] [cgi:error] [pid 21969] [client xxx] 
AH01215: compiled template : Can't locate 
/tmp//usr/share/koha/opac/htdocs/opac-tmpl/bootstrap/en/modules/opac-main.tt.ttc: 
   
/tmp//usr/share/koha/opac/htdocs/opac-tmpl/bootstrap/en/modules/opac-main.tt.ttc: 
Permission denied at 
/usr/lib/x86_64-linux-gnu/perl5/5.28/Template/Provider.pm line 571.: 
/usr/share/koha/opac/cgi-bin/opac/opac-main.pl
[Thu Sep 23 14:36:17.088598 2021] [cgi:error] [pid 21969] [client xxx] 
AH01215: : /usr/share/koha/opac/cgi-bin/opac/opac-main.pl
[Thu Sep 23 14:36:17.118243 2021] [cgi:error] [pid 21969] [client xxx] 
AH01215: Template process failed: file error - cache failed to write 
opac-main.tt.ttc: Error in tempfile() using template 
/tmp/usr/share/koha/opac/htdocs/opac-tmpl/bootstrap/en/modules/XXXXXXXXXX: 
Could not create temp file 
/tmp/usr/share/koha/opac/htdocs/opac-tmpl/bootstrap/en/modules/Ti3EjV0TMw: 
Permission denied at 
/usr/lib/x86_64-linux-gnu/perl5/5.28/Template/Document.pm line 301.: 
/usr/share/koha/opac/cgi-bin/opac/opac-main.pl
[Thu Sep 23 14:36:17.156177 2021] [cgi:error] [pid 21969] [client xxx] 
End of script output before headers: opac-main.pl
[Thu Sep 23 14:36:18.597239 2021] [cgi:error] [pid 21969] [client xxx] 
AH01215: Use of uninitialized value $compiled in concatenation (.) or 
string at /usr/lib/x86_64-linux-gnu/perl5/5.28/Template/Provider.pm line 
572.: /usr/share/koha/opac/cgi-bin/opac/errors/500.pl
[Thu Sep 23 14:36:18.597997 2021] [cgi:error] [pid 21969] [client xxx] 
AH01215: compiled template : Can't locate 
/tmp//usr/share/koha/opac/htdocs/opac-tmpl/bootstrap/en/modules/errors/errorpage.tt.ttc: 
   
/tmp//usr/share/koha/opac/htdocs/opac-tmpl/bootstrap/en/modules/errors/errorpage.tt.ttc: 
Permission denied at 
/usr/lib/x86_64-linux-gnu/perl5/5.28/Template/Provider.pm line 571.: 
/usr/share/koha/opac/cgi-bin/opac/errors/500.pl
[Thu Sep 23 14:36:18.598021 2021] [cgi:error] [pid 21969] [client xxx] 
AH01215: : /usr/share/koha/opac/cgi-bin/opac/errors/500.pl
[Thu Sep 23 14:36:18.613489 2021] [cgi:error] [pid 21969] [client xxx] 
AH01215: Template process failed: file error - cache failed to write 
errorpage.tt.ttc: Error in tempfile() using template 
/tmp/usr/share/koha/opac/htdocs/opac-tmpl/bootstrap/en/modules/errors/XXXXXXXXXX: 
Could not create temp file 
/tmp/usr/share/koha/opac/htdocs/opac-tmpl/bootstrap/en/modules/errors/mVp8iM_cko: 
Permission denied at 
/usr/lib/x86_64-linux-gnu/perl5/5.28/Template/Document.pm line 301.: 
/usr/share/koha/opac/cgi-bin/opac/errors/500.pl
[Thu Sep 23 14:36:18.646433 2021] [cgi:error] [pid 21969] [client xxx] 
End of script output before headers: 500.pl
```

The ownership of /usr/share/koha/{intranet,opac} is set to the user 
www-data.
The ownership of /etc/koha/sites is set to the user koha_koha.

Any help would be greatly appreciated.

Thanks!

Jacopo