INAV 9.1 is primarily a **maintenance release** focused on reliability improvements, safety fixes, and GPS accuracy. Since 9.0.1: **46 fixes** and **76 new features/enhancements**, including 19 new hardware targets. It contains no incompatible settings changes — your 9.0.x `diff all` will load cleanly.
For full PR-by-PR detail, see the [wiki release notes](https://github.com/iNavFlight/inav/wiki/9.1.0-Release-Notes).
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##### Upgrading from INAV 9.0.x
1. Download and install the new [INAV 9.1 Configurator](https://github.com/iNavFlight/inav-configurator/releases)
2. Backup your configuration: CLI → `diff all` → save to file
3. Flash INAV 9.1.0 — **Full Chip Erase is NOT required** when upgrading from 9.0.x
4. Restore settings from CLI or use the _Keep current settings_ option
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##### Upgrading from INAV 8.x
1. Download and install the new [INAV 9.1 Configurator](https://github.com/iNavFlight/inav-configurator/releases)
2. Backup configuration: CLI → `diff all` → save to file
3. Flash INAV 9.1.0 **WITH** _Full Chip Erase_ enabled
4. Load your 8.x diff into the CLI; note any settings shown in RED
6. Use the [INAV CLI Update Tool](https://mrd-rc.com/iNav/INAV-CLI-Update.php) or manually update incompatible settings from the 9.0.0 release notes
7. See [Upgrading from an older version](https://github.com/iNavFlight/inav/wiki/Upgrading-from-an-older-version-of-INAV-to-the-current-version) for full instructions
> [!NOTE]
> The INAV 9.1 Configurator includes a settings migration tool in the CLI tab that can assist with upgrading from older versions.
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##### ⚠️ Important Notes for 9.1
###### FLYINGRCF4WINGMINI alignment change
If you have the FLYINGRCF4WINGMINI, you will need to re-do the accelerometer alignment, as the gyro rotation has been corrected.
###### GPS Default Settings Changed
Two GPS defaults have changed. These only affect you if you never explicitly set them in your configuration (i.e., they are not in your `diff all`):
- **`gps_ublox_nav_hz`** default changed from **10 → 8 Hz**. Lower rate allows more satellite constellations to be tracked for better accuracy, especially on M8/M9 modules. If you want to keep 10 Hz, add `set gps_ublox_nav_hz = 10` to your diff.
- **`gps_ublox_use_galileo`** and **`gps_ublox_use_beidou`** now default to **ON**. More constellations generally improves position accuracy.
###### Position Estimator — Altitude Controller Gains
> [!WARNING]
> If you have increased `nav_mc_pos_z_p` or `nav_mc_vel_z_p` above their default values since INAV 7.1, it is advisable to **lower those gains or re-tune them** to avoid possible throttle oscillations in navigation modes that control altitude (WP, Cruise, RTH, and forward-flight Poshold).
>
> The improved position estimator relies more on accelerometer weighting, so ensure your multicopter or VTOL is free from propeller and motor vibrations. See [Multirotor filter setup](https://github.com/iNavFlight/inav/wiki/Multirotor-guide#5-selecting-filters) for tips.
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##### Highlights
###### GNSS Constellation and Update Rate
INAV now provides an optimized GPS update rate based on your hardware type (M8, M9, M10) and the number of active constellations.
_[Truncated at 4000 characters — full notes: https://github.com/iNavFlight/inav/releases/tag/9.1.0]_
### 9.1.0-RC1 — INAV 9.1.0-RC1 release candidate for testing
- Date: 2026-06-05
- Version: 9.1.0-RC1
- Original notes: https://github.com/iNavFlight/inav/releases/tag/9.1.0-RC1
- Permalink: https://whatsnew.fyi/product/inav/releases/9.1.0-rc1
- Labels: Pre-release
- **changed** — GPS ublox navigation rate default changed from 10 Hz to 8 Hz to allow tracking more satellite constellations for better accuracy
- **changed** — GPS ublox Galileo and Beidou constellation support now enabled by default
- **added** — Multicopter magless heading mode allowing navigation without a compass by pointing the aircraft toward known North before takeoff
- **changed** — Position estimator improved to enhance multicopter position hold accuracy during poor or fluctuating GPS signal
- **changed** — OSD post-disarm stats now correctly display CRSF RX data, saving settings, and disarmed by advisories on HD displays
- **changed** — OSD multifunction mode expanded with battery voltage and capacity warnings, pitot failure alerts, and compass calibration indicators
- **added** — Toilet-bowl compass deviation warning added to Poshold multicopter mode
- **changed** — Surface mode and Geozone system messages improved
- **fixed** — Servos no longer output wrong position when disarmed with reversed throttle mix
- **fixed** — RTH Trackback flight controller lockup in certain scenarios prevented
- **fixed** — Motor 1 random spin-up after disarming with BLHeli_32 32.9 and earlier firmware fixed
#### Welcome to INAV 9.1.0-RC1
Please carefully read all of this document for the best possible experience and safety.
Contact other pilots, share experiences, suggestions and ask for help on:
