The set-up:
1. Create a host group "A";
2. Create a template "T";
3. Assign template "T" to host group "A";
4. Create a host group "B";
5. Create a host "H";
6. Assign host "H" to host group "B";
7. Link template "T" to host "H";
8. Create a user group "G";
9. Set "Read-write" permissions to host group "A";
10. Set "Deny" permissions to host group "B";
11. Create a user "U";
12. Assign user "U" to group "G";
13a. Set "User type" to "Zabbix Admin" (for 4.0);
13b1. Create user role "R" and set "User type" to "Admin" (for 5.2 and higher);
13b2. Assign role "R" to user "U" (for 5.2 and higher);
14. Create host prototype on template "T";

The execution:
1. Log in with user "U" (regular admin);
2. Export template "T";

Result:
a) Observe ambiguous error "No permissions to referred object or it does not exist!" (for 4.0);
b) Observe the page reloads, but nothing happens (for 5.2 and higher).

Expected:
If user is not allowed to access the group, then perhaps some better error message is expected. For example "Cannot exported template because it contains an inaccessible group."