This anomaly applies to Revision 2, build code CAAA-Bxx.
It was inherited from the previous SoC revision Revision 1.
Symptoms
Full flash erase through CTRL-AP is not successful.
Conditions
WDT is enabled.
Consequences
Flash is not erased. If the device has a WDT time-out less than 1 ms and is readback-protected through UICR.APPROTECT, there is a risk of permanently preventing the erasing of the flash.
Workaround
Try again.