I want to share an interesting case about updating the firmware over FOTA..
I have several nodes on a RS485 bus with memory chips.
Recently I decided to update the firmware on several at once and ran into an unexpected problem - repeated attempts to update constantly ended up with a checksum error !OTA:FWP:CRC FAIL.
At the same time, I usually test all new nodes for FOTA firmware updates before installing.
I tried to understand what the problem might be and came to an unexpected result - in my case, disabling the directive OTA_EXTRA_FLASH_DEBUG, which I had been using for a long time, when I first tested updates, helped.
After disabling this directive, all firmwares were updated the first time. Very strange, but nevertheless ...