Steps to reproduce:

1. Navigate to Configuration -> Hosts/Templates;
2. Enter some Host or Template with Discovery rules;
3. Select Host/Trigger/Item prototype sub-section (there must be records);
4. Enable or disable prototype record using Yes/No button in "Create enabled" column;
5. Once the page is reloaded, try to create a new prototype.

Result:
Error message: "Zabbix has received an incorrect request. Operation cannot be performed due to unauthorized request."