The following advice had been given to us by Turnitin, who advise that this issue is likely caused by the privacy settings enabled in your browser.
If you see an error message that says ‘invalid state’ when trying to launch Turnitin, please use the following the steps to ensure that your preferred browser reflects the correct preferences:
In Firefox, select File > Preferences > Privacy & Security. If Strict is enabled, please change this to Standard.
Once you have completed reviewing your browser’s Privacy & Security preferences, please close the browser and re-open a new browsing session so that any changes can take effect.
If the issue still persists after applying these settings, please report this to the IT Service Desk.