Flash Download Tool Combined BIN file erases stored NVS data

[Josy_Rausch]

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:

Screenshot 2026-06-12 105700.png (69.12 KiB) Viewed 70 times

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?

[Sprite]

'Any unused area between firmware files will be filled with FF' - and I bet that the NVS area is somewhere between your bootloader and app. Solution, if you insist on flashing the combined binary, would be to customize your partition table so the NVS partition comes after the app partition.

[Josy_Rausch]

'Any unused area between firmware files will be filled with FF' - and I bet that the NVS area is somewhere between your bootloader and app. Solution, if you insist on flashing the combined binary, would be to customize your partition table so the NVS partition comes after the app partition.

Alright, Thank you.