This error is usually received when attempting to set parameters and activate the device after registering under the my devices page.
This is a known connection error that is typically found in older devices that are not up to date on firmware. Check the status of your firmware to be sure you are up to date to v 0.16.0. Please see the article on how to check your firmware. https://purplscientific.freshdesk.com/a/solutions/articles/64000263077
If you need to complete the firmware update please see the articles below:
Firmware v 0.16.0 Dark Measurement Fix
VCP Driver Install for USB Interface Connection
If you are up to date on firmware, try rebooting your phone and completing the 10 Second Device Reset method.
Resetting the Purpl Pro: https://purplscientific.freshdesk.com/a/solutions/articles/64000251196
If you complete the reset and are up to date on firmware and continue to receive the error please reach out to Tech Support at purplhelp.com and submit a ticket.