Experience 3005 error when try to login.
This occur when the device sends an invalid request.
Update your Zscaler Client Connector to its latest version.
Try to Log in again.
if issue still occur try to check the WMI.
On your device (PC/Laptop), open Windows Powershell (Admin) and paste the command below.
Get-CimInstance -ClassName Win32_ComputerSystem
If it gives the error, maybe WMI is corrupted, Please resolve them same by following below link.
or run this command in the Window Powershell (Admin).
cd %windir%\system32\wbem for /f %%s in ('dir /s /b .mof .mfl') do mofcomp %%s
if no issues on WMI you may proceed to next step below.
If issue still occurs, you may escalate this to next level, raised a support ticket to Zscaler TAC Support and attached the logs from Zscaler Client Connector.