I went to country side with only my modular, no computer. Wanted to use the ER 301 as a mixer/recorder but I got this message when I started recording only 1 output!
I use the SD I got when I bought my ER 301.
I used only couple of basic effects…I don’t understand?! 
Probably, your SD card has become fragmented. Copy everything to your PC, wipe the card (or reformat using the ER-301), and then copy everything back.
…I forgot to take the micro/SD adaptor. Will check next week…thanks Brian.
Just to let you know, it worked. Formatted the SD car using the ER-301. 
