Most of such issue is caused by memory card. Firstly try formatting the SD card using the option in the Dash Cam Settings Menu. You can check this guide about how to format the memory card.
If Re-Formatting the SD Card does not resolve the problem, then try removing and re-inserting the SD Card.
If Re-inserting does not resolve the problem then please try using a different Micro SD Card. We suggest you use VIOFO or Transcend memory card for VIOFO Dash camera.
You can buy VIOFO memory cards from below link.