Error messages, not reported by the GUI:

E1: mp3 SPI I/O never finished (may not happen)
E2: MMC SPI I/O never finished (may not happen)
E4: mp3 decoder (DREQ signal) does not get ready (serious, not correctable, only a full power off helps)
E5: mp3 data pause requested, but was already the case (may not happen)
E6: SPI and Timer3 interrupt were active at the same time (may not happen)
E7: Invalid mp3 sourcetype state (can happen, maybe EEPROM corruption or first boot)
E8: Invalid jump back to main (may not happen)
E10: Path append failed, because path too long (can happen)
E11: Stats checksum error (can happen, maybe EEPROM corruption or first boot)
E12: File path requested without active directory listing (may not happen)
E13: File part requested without buffer (may not happen)
E14: Event queue overflow (may happen)
E15: Could not write as much as expected while recording (should not happen)
E16: manager_filenameget returned NULL (should not happen)
E17: Selected file is NULL (can happen if the file got deleted before)