This can be a common issue if you are not able to connect to the Database. This error occurs if the Database is out of memory, the system is spiked or that SharePoint goes into sleep mode. SharePoint will need to be restarted or refreshed in order for it to be fully functional again. This ultimately seems to be an intermittent Atera Settings DB connectivity issue.
A fix can be applied for this issue by activating and deactivating the feature that is causing the error, then reloading/refreshing the page.
Go to Site Settings > then Site Collection Features under the Site Collection Administrators category. Deactivate then Reactivate the feature. Refresh the page when finished.
If this error persists, please use the execution files provided below to run in your environment. These execution files will look for the faulty features in your farm then deactivate and remove them.
Note: After successfully completing the execution of the exe, you will need to manually activate features which are deactivated by the exe files.
Please contact Emgage Support for any additional assistance or inquiries.