This error means the client app couldn't get the task ID from the server,
1. Analyze again.
2. Access the installation path(click on the client app icon in the desktop by the right button, select 'open file location'), double-click on Clenup.bat to close the app, then restart the app. Close 360 or other anti-virus softwares and reinstall the client app if it doesn't work after many trials but there is no problem with the network connection. Because there might be some files blocked by the anti-virus software.
3. Report this error to the online customer service on www.renderbus.com, they will contact the R&D department to fix it.