Remove the memory card and then reinsert it. Make sure it's inserted in the correct direction and not at a slant.
Note: Refer to the camera Help Guide for details on the direction in which the memory card should be inserted.
Check if the memory card terminals are clean.
WARNING! There is a risk of software corruption. Don't touch the memory card terminals with your hands or any metal object.
Wipe dirty memory card terminals with a dry cloth or cotton swab.
If you're using a MicroSD or Memory Stick Micro memory card with an adapter:
Make sure that the memory card is inserted in the adapter correctly.
Try a different adapter or another memory card to isolate the issue.
If possible, use a full size SD™ or Memory Stick™ memory card instead of a MicroSD or Memory Stick Micro memory card with an adapter. MicroSD and Memory Stick Micro memory cards are recommended for the use in smaller devices like mobile phones or action cameras.