Flash Download Tool Combined BIN file erases stored NVS data
Posted: Tue Jun 16, 2026 8:14 am
Hello,
I am using the Flash Download Tool to flash binaries to my ESP32-C6-WROOM-1.
I store some important data (a bool and an unsigned integer value) in NVS, and this works correctly because after a power restart I can still read the saved data.
When I make changes to my program and build it, the binary files are generated.
If I flash each binary file separately (bootloader.bin, partition_table.bin, and app.bin) and then perform a power restart, the NVS data is not deleted.
However, when I combine the three binary files into one and flash this single binary file, my saved NVS data gets deleted.
I understand from the documentation that this can happen when using the “combine” option:
I would expect, however, that flashing the three binaries separately or flashing a combined binary should behave in the same way.
Am I doing something wrong?
How can I prevent the NVS data from being erased when using the combined binary method?
I am using the Flash Download Tool to flash binaries to my ESP32-C6-WROOM-1.
I store some important data (a bool and an unsigned integer value) in NVS, and this works correctly because after a power restart I can still read the saved data.
When I make changes to my program and build it, the binary files are generated.
If I flash each binary file separately (bootloader.bin, partition_table.bin, and app.bin) and then perform a power restart, the NVS data is not deleted.
However, when I combine the three binary files into one and flash this single binary file, my saved NVS data gets deleted.
I understand from the documentation that this can happen when using the “combine” option:
I would expect, however, that flashing the three binaries separately or flashing a combined binary should behave in the same way.
Am I doing something wrong?
How can I prevent the NVS data from being erased when using the combined binary method?