When this happens, it usually means that there has been a loss in signal/connection and no project has been created on the web app.
In turn, the app can't figure out where to send the files, and this results in an error message, a crash or a freeze on the app.
To fix this, you may need to create a new project and session on the web app and manually link those new details into the iPhone app afterwards.
This is the screen on the iPhone app where you will need to input the new details that you will retrieve from the web app:
If there are numbers already in the boxes, this means that the iPhone app has created a project and session on the web app ready for you to upload your videos. (but this might still be causing an issue, so please continue with the troubleshooting)
The camera number for the host device will be -1 by default.
The capture devices will have different "cam numbers" depending on when they were connected to the host device.
NEXT: 3. How to create a new session and update the details in the iPhone app?