OTA-only upgrade path for the partition table breaking change using ESPHome CLI

[ethem]

The 2026-05-26 release notes require a one-time factory flash for the new partitions_16mb.csv, pointing to install-from-bin.md which uses web.esphome.io - requiring USB and a Chrome/Edge browser.

If you build the firmware from source (as described in build-from-source.md), there's a fully wireless alternative introduced in ESPHome 2026.5.1. See ESPHome docs: Updating the Partition Table on ESP32.

I can confirm this works.

Note: This does not apply to users flashing the precompiled .bin files - for those, the USB + web.esphome.io path from install-from-bin.md remains the only option.

Step 1 - Add allow_partition_access and flash via OTA (normal app update)

Add to your OTA config:

ota:
  - platform: esphome
    allow_partition_access: true

Flash your current firmware with this change - do not update to the latest release yet:

esphome run --device <IP> your-config.yaml

Step 2 - Flash the new partition table over the air

esphome upload --partition-table --device <IP> your-config.yaml

Step 3 - Flash the full firmware with the latest release

esphome run --device <IP> your-config.yaml

[gekkekoe]

From source + usb is really easy:
esphome run --device /dev/ttyxxx your-config.yaml
Just be sure to use usb, and not over ip. The partition table is automatically flashed when flashing via usb.

The new wireless method is convenient if you don't want to unmount Asgard.

[ethem]

Exactly - that's the key use case: Asgard is mounted inside the heat pump enclosure, so avoiding disassembly is the main motivation. Good to know USB also handles the partition table automatically.

[gekkekoe]

Yeah, or just turn off power, circuit breaker off (wait couple of mins), and then plug in usb and flash it from a laptop. (then you can leave it mounted)