Trimble ERR020 Error: What It Means and How to Fix It

Applies to: R8, R10, SPS986, R12

What Does ERR020 Mean?

ERR020 on Trimble GPS receivers means the base and rover are configured with incompatible settings — most commonly a corrections format mismatch but also possible from firmware version incompatibility or conflicting coordinate system settings. The rover is receiving corrections but can't use them because they're in the wrong format or from an incompatible base configuration.

ERR020 is one of the most frustrating errors because everything appears to be working — the radio link is up, corrections are flowing — but the rover still can't achieve a fix. The fix is always a configuration change, not a hardware repair.

Common Causes of ERR020

• Base transmitting RTCM 2.3 corrections but rover configured to receive CMR or RTCM 3.2
• Base and rover running different firmware versions that have changed correction format handling
• Coordinate system or datum configured differently on base and rover — positions in different datums can't be combined
• Antenna height entered incorrectly on base — this doesn't cause ERR020 directly but can produce position errors that trigger quality flags
• Base transmitting on multiple correction formats and rover locked to the wrong one

How to Fix Trimble ERR020 — Step by Step

1. Check correction format on the base: in Trimble Access, Survey > Base Options > Output Corrections. Note the format (RTCM 2.3, RTCM 3.2, CMR, CMR+).
2. Check correction format on the rover: Survey > Rover Options > Input Corrections. Match it exactly to the base output.
3. Confirm both base and rover are using the same coordinate system and datum.
4. Update firmware on both units to the same version if there's a discrepancy.
5. Power cycle after changing any settings — format changes don't take effect until restart.
6. If using a third-party base (not Trimble), confirm the correction format output is compatible with Trimble rover firmware.

When to Send It In for Service

ERR020 is always a configuration issue, not hardware. No service required.

Preventing ERR020 in the Future

Document base and rover settings at the start of every project. When mixing equipment from different sources, explicitly verify correction format compatibility before mobilizing to the field.

Related Error Codes

Trimble Gps Error Err001 | Trimble Gps Error Err005 | Trimble Gps Error Err021