One Wrong Target Can Break the Update: Flashing ELRS Safely
Quick Answer
Check the firmware version and hardware target before flashing. Update serial ExpressLRS transmitters and receivers with the official Configurator or Web Flasher, using the same major version, frequency band, regulatory domain and binding phrase on both ends. ExpressLRS 4.1.0 is the current stable release, but 4.x cannot connect to 3.x.
Check Before You Update
Open the ExpressLRS Lua tool on your handset to read the transmitter version. For a connected serial receiver, use the Lua tool’s device list; if it will not connect, check the receiver Web UI or its startup message in Betaflight. The first version number must match: 4.1.0 can work with another 4.x device, but not with 3.x.
Do not choose a target by brand name alone. The Configurator requires the exact device category and hardware target; it does not safely identify every module for you. Record the current target, binding phrase, band and regulatory domain first. ExpressLRS 4.0 also changed the flash filesystem, so export any custom hardware.json and Web UI options before moving from 3.x.
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, download the official ExpressLRS Configurator, select Official Releases, then choose the exact target and method. Binding settings must agree at both ends. Most UK FPV builds use 2.4GHz hardware; 868MHz and 915MHz are not interchangeable regulatory-domain labels.
Update the Transmitter First
For an internal module, select EdgeTXPassthrough. For an external module, use the connection method listed for that target. Build and flash, then reopen the Lua tool and confirm the reported version instead of assuming a green progress bar proves 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.
If you have several older SPI whoops, keeping one transmitter module on 3.x can be less disruptive than migrating every aircraft at once. Our ELRS binding guide covers the final bind checks, while the telemetry guide handles link-data setup after the update.
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 the current stable release. Verify the official release page before flashing because this answer 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.