This error is seen during the installation or upgrade of the Management Center to 8.2. IIS reports that the VERBS used in the two HandlerMappings are set to ALL, but they are denying GET, which is what is needed for the Diagnostic Upload.
Within IIS, expand to the ManagementServer\Deployment\Events area.
On the right hand pane, open HandlerMappings. There will be two listed: BitsHandler and StaticFile.
Right click on each of these items and select REMOVE. Press Yes to each confirmation to remove.
Once empty, open up your Management Server Configuration Utility. There will be a list of variances relating to the Handler Mappings.
Select the REPAIR ALL button. This action may take a moment to complete.
Once all variances report success, refresh to confirm.
Confirm in IIS that the HandlerMappings have re-appeared.
Once you have confirmed the above, open a Command Prompt as Administrator and run IISRESET /RESTART
Once all IIS Services have restarted, please retest diagnostics on your endpoints.