A customer logged into POA Control Panel (which is working on Windows server), selected an item in the large list and performed operation on it, for example, remove Exchange public folder,
Operation fails with error '400 Bad Request'.
The reason is the default IIS security policy - it does not allow URL to contain more than 255 sections, divided by '/', in order to reduce the risk of file system traversal attacks.
1. Run the regedit on IIS server wher POA Control Panel service is running.
2. Add the registry key HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Services\HTTP\Parameters\UrlSegmentMaxCount with the value dword:0.
3. Reboot the server (it is not enough to run iisreset).