When viewing web scenarios filtered by host group only (without selecting a specific host), selecting multiple web scenarios and clicking Enable/Disable results in the error:

No permissions to referred object or it does not exist!

Steps to reproduce:

1. Create a host group with at least 2 hosts, each having one or more web scenarios
2. Go to Data collection > Hosts > and select a group with web scenarios
3. Click Web on one of them
   
   Change view by host, from
   
   To group:
   
4. Leave Hosts field empty.
5. Click Apply - web scenarios from both hosts are listed.
6. Select multiple web scenarios using checkboxes.
7. Click Disable or Enable at the bottom of the page.

Result:

Expected:
Selected web scenarios are disabled or enabled.

Root cause:
Permission check in httpconf.php for bulk actions

elseif (hasRequest('hostid') && !isWritableHostTemplates([getRequest('hostid')])) {
    access_deny();
}