Cannot Arm in any GPS mode: 16 sats, .7 HDOP 3D Fix = Error: No 3D Fix

Like the title states I cannot get my copter to fly. It has an excellent GPS lock etc but will not arm in Loiter or any other GPS required modes. I have fooled around with Arming checks and serial baud rate and nothing has an impact. Shows “3D Fix” on bottom right of HUD. Firmware version 4.0.7

Please see attached log file.
Thank you2021-06-08 11-29-25.tlog (921.8 KB)

I rolled back to 4.0.3 and used all the same parameters and everything works as normal and I can arm in Loiter like normal.

Having the same symptoms. Reverting back to 4.0.3.

Did you try just rebooting to see if it clears the error?
In Copter 3.6.x, I have had a few incidents where I get the 3D Fix error with good GPS, and rebooting makes it go away.

Yes, many times. No change.

Tlog isn’t of much value. Post a link to a .bin log

Bin logs attached

2021-06-08 11-30-06.bin (501.2 KB) 2021-06-08 11-15-58.bin (486 KB)

I think it is related to the Geo Fence. I built another copter using 4.0.7 and everything was great including being able to arm in Loiter. After I set the Geo Fence it no longer allows me to arm, keeps saying “Prearm: 3D Fix.” Even when I disable the Geo Fence this error still comes up.

Do you see these messages and then the EKF indicator goes from red to white? Then you have a fix the EKF is happy with.

No time to test. Rolled back to 4.0.3. Hopefully someone can figure it out in the meantime.

If 4.0.3 has a bug that does not correctly validate the GPS data, going back to 4.0.3 is not a solution.

My guess is that you need to correctly setup your fence

@amilcarlucas sure thing I would love for it to work. If 4.0.3 has a bug with GPS data, surely 4.0.7 can also have a bug with GPS data?

Do you have advice for me? I set geo fence as circle and altitude. 200m altitude and 2000m circle. Then I disabled it. It’s pretty simple, not sure how I could be doing it “incorrectly.” Please give me a list of parameters to use.

Which GPS receivers do you use? I went trough the 4.0.4 … 4.0.7 release notes and there are bug fixes for some RTK GPSs…

Here+ RTK GPS ,

How about not disabling the fence?

And then what? I tried with it enabled and disabled.

Can you bisect the problem? Test with 4.0.6, 4.0.5 and 4.0.4 ?

Same issue using 4.0.5. In Messages IMU1 and IMU0 never use GPS.

So the problem was introduced in either 4.0.4 or 4.0.5.
Now we are getting somewhere.

Getting tired of Arducopter and all the issues. Moving the copter to PX4