The [Memory card locked] message appears on the screen (EOS M3)
05-Feb-2015
8202334200
Solution
The SD memory card, SDHC memory card, SDXC memory card or Eye-Fi cards have a write-protect tab.
If the [Write Protect Tab] is in the locked position, the following screen appears.
During shooting: [Memory card locked] appears in the upper portion of the screen, and shooting is not possible.
During playback: If you try to delete an image and [Memory card locked] appears in the lower portion of the screen, the image cannot be deleted.
If [Memory card locked] appears on the [LCD Monitor] of the camera, 
the [Write Protect Tab] of the memory card being used is in the 
locked (downside) position, so you cannot capture or delete images.
the [Write Protect Tab] of the memory card being used is in the locked (downside) position, so you cannot capture or delete images.To unlock the tab, slide 
the [Write Protect Tab] of the memory card upward.
the [Write Protect Tab] of the memory card upward.