There were X render elements before rendering, but now there are Y. Adding/removing render elements during rendering is not supported. No render elements will be saved

This message is triggered by adding, removing, or changing render elements during rendering. Corona will not save render elements at the end of the current rendering session to prevent instability and possible errors/crashes.

Possible causes:

• Render elements count has been changed during rendering
• Individual render elements have been changed, while maintaining the total number of them

Solutions:

• Never add, remove, or change render elements and their parameters during rendering.
• If you do change render elements during rendering, Corona will not save the render element files to prevent instability. You can still manually save render elements from the Corona VFB, so they are not inevitably lost.

See: Render Elements
Videos: Saving all render elements at once , CESSENTIAL elements