Getting error "Access Denied" You are logged in as 'Admin'.

[rxm8028]

Full message states: "Access Denied" You are logged in as 'Admin'. You have no permissions to access this page." Then some text about contacting the administrator.

After upgrade from 3.4 to 4.0, my 'Admin' user can no longer bulk acknowledge any problems, or acknowledge ANY problem that is 'unresolved', as far as I can tell. Anyone have an idea why this might be?

The user name 'Admin' is a member of the 'Zabbix Administrators' group, and is user of type 'Zabbix Super Admins'.

The manual says that Zabbix Super Admins have read/write privileges on everything by default. It is not possible for me to add 'Admin' to any groups for specific permissions. I assume this is because Admin is a default read/write user already, but perhaps there is something broken?

[Atsushi]

Have you cleared the browser's cache?

Manual : 8 Clear web browser cookies and cache

https://www.zabbix.com/documentation/4.0/manual/installation/upgrade/packages/rhel_centos

https://www.zabbix.com/documentation/4.0/manual/installation/upgrade/packages/debian_ubuntu

[rxm8028]

I was forced to manually clear a great deal of history, events, and problems from the zabbix db. This seems to have fixed my problem. I suspect that there were orphaned records, and clearing the entire table fixed the dependencies.

[Shexa]

I was having the same issue when I was trying to import a template. Zabbix was displaying "Access denied" and here is how I resolved it:
I just changed ownership of my xml file from root user and I was able to import it
the command I used:

chown myNormalUserNotRootUser: myTemplate.xml