One Wrong Target Can Break the Update: Flashing ELRS Safely

Quick Answer

Check the version and exact target before flashing serial ExpressLRS hardware with the official Configurator or Web Flasher. TX and RX must share a major version, band, regulatory domain and binding phrase. ExpressLRS 4.1.0 is current; 4.x cannot connect to 3.x.

Check Your ELRS Version in 60 Seconds

The version is major.minor.patch. The first number controls compatibility: 4.1.0 can connect to another 4.x device, but not to 3.x. Check the receiver before treating a bind failure as a reason to flash.

Device	Where to read the version
TX module	Open the ExpressLRS Lua tool and read the version line near the bottom
Bound serial RX	Lua tool → Other Devices → select the receiver
Unbound serial RX	Enter Wi-Fi mode, join ExpressLRS RX, then read the Web UI banner at 10.0.0.1
SPI RX in an AIO	Check the Betaflight firmware version and its ELRS protocol build option

The official firmware-version check shows both Lua and Web UI routes. Before a 3.x-to-4.x migration, record the exact target, binding phrase, band and regulatory domain, then export custom hardware.json and Web UI options: ExpressLRS 4.0 changed the flash filesystem.

Which Update Method Should You Use?

Hardware	Best first method	Use instead when
External TX module	Wi-Fi or direct UART/USB, as supported by the module	Use the vendor’s documented boot method if the normal flash fails
Internal ELRS radio	EdgeTX Passthrough in Configurator	Use Wi-Fi when the module starts its access point correctly
Serial receiver on a flight controller	Betaflight Passthrough	Use Wi-Fi if passthrough cannot initialise the receiver
Loose serial receiver	Wi-Fi	Use a 3.3V-compatible UART adapter for recovery
SPI receiver built into an AIO	Flash Betaflight, not ELRS Configurator	There is no separate receiver firmware file

For serial hardware, use the official ExpressLRS Configurator, select Official Releases, then choose the exact target and method. Most UK FPV builds use 2.4GHz hardware; 868MHz and 915MHz are not interchangeable labels.

Update the Transmitter First

For an internal module, select EdgeTXPassthrough; for an external module, use the method listed for that target. Build and flash, then reopen the Lua tool and confirm the reported version. A green progress bar alone does not prove the radio is ready.

The BetaFPV ELRS Nano TX Module is sold in different frequency versions, which is exactly why the target and band check matters.

Update a Serial Receiver

Betaflight Passthrough is normally the cleanest route when the receiver is already wired: close Betaflight Configurator, connect the flight controller by USB, select the exact receiver target and flash. Receivers such as the SkyGuy Nano 2.4GHz receiver and GEPRC ELRS Nano Dual are serial devices, not SPI receivers.

For Wi-Fi, enable receiver Wi-Fi from the Lua device menu while linked. If it is not linked, leave the receiver powered until its automatic Wi-Fi interval expires, or use its documented boot-button method. Join ExpressLRS RX, browse to http://10.0.0.1, and upload the generated firmware.bin.gz without extracting it. A receiver configured for home Wi-Fi may appear at elrs_rx.local instead of creating an access point.

SPI Whoops Need a Different Process

An SPI receiver is part of the flight-controller firmware. Betaflight 2026.6 supports the ExpressLRS 4 protocol, but new firmware builds default to ELRS 3. To use a 4.x transmitter, add ELRSV4 to the build flags in Betaflight Firmware Flasher; that build will then be incompatible with an ELRS 3 transmitter. Back up diff all, verify the correct flight-controller target and restore settings carefully after flashing.

For several older SPI whoops, keeping one transmitter module on 3.x may be simpler than migrating every aircraft. Use our ELRS binding guide for final checks and the telemetry guide for link-data setup.

Common Failures

No bind after flashing: compare the major version, frequency band, binding phrase and regulatory domain. No device in Configurator: close other serial applications, try a known data cable and re-check the selected target. No Wi-Fi access point: the device may have joined saved home Wi-Fi; try elrs_tx.local or elrs_rx.local. Two ExpressLRS tools: install the current elrs.lua and remove old elrsV3.lua or compiled copies.

See our ELRS explainer, receiver selection guide and radio-control collection for compatible hardware and background.

FAQ

Q: What is the latest stable ExpressLRS version?

A: ExpressLRS 4.1.0 is current. Verify the official release page before flashing because this will change.

Q: Can ExpressLRS 3 and 4 bind together?

A: No. Transmitter and receiver must share the same major version. Minor and patch versions can differ within that major version.

Q: Does updating always erase the binding phrase?

A: Not always, but a 3.x-to-4.x migration changes the filesystem and can remove custom Web UI options. Record the phrase and export custom configuration before updating.