We have identified an issue in the latest firmware for the APEX Pro and VERTIX - v 3.0508.0 released 7 Aug 2024. Regretfully, the issue affects the accuracy and integrity of speeds being recorded by the APEX Pro and VERTIX. We recommend that APEX Pro and VERTIX users do not upgrade to firmware v 3.0508.0. 

Users who have already upgraded, but own another verified device are requested to post from that device when possible. Our tech crew, supported with technical expertise from our community is actively working with COROS to get this issue resolved ASAP, and we will keep you updated.  For now we advise to avoid competitions to run on max 2s speed or on single 10sec runs, we recommend to use the 5x10s AVG or 500meters instead.

GP3S Crew

I have tried to illustrate the issues by driving around a short test circuit; 3 laps with total distance of 5 km. These show what is "normal" for these firmware releases but much bigger issues are evident in real session data.

https://logiqx.github.io/gps-details/devices/coros/windsurfing/

My advice would be to avoid any firmware release since May 2024 - 3.0408.0 / 3.0409.0 upwards, especially 3.0508.0 on the APEX Pro / VERTIX. If you have an APEX Pro or VERTIX, you can downgrade to a working firmware (3.0309.0) using the instructions at support.coros.com/hc/en-us/articles/15344945273620-How-to-manually-update-my-COROS-watch

I've not managed to downgrade my APEX 2 Pro (yet), although I believe it should be possible. If anyone has any luck downgrading their APEX 2 / APEX 2 Pro / VERTIX 2 / VERTIX 2S then please let us know how to do it.

Just bought a new Coros yesterday, especially for this site. Does this issue also include the Apex2Pro and Vertix2?

The APEX 2 Pro and VERTIX 2 are affected, but to a lesser extent than the APEX Pro and VERTIX.

Be sure to use all systems or dual frequency (not regular GPS) to minimise the effects.

If you are on firmware 3.0309.0 (or earlier) then it is advisable not to upgrade, until COROS resolve the issue.

COROS are aware of the issue and working on a fix.

Is there anything new about the faulty firmware 3.0508.0?

I wanted to downgrade but I can't open this page --> support.coros.com/hc/en-us/articles/15344945273620-How-to-manually-update-my-COROS-watch

Apparently I'm not authorized to open this page?!
Can someone send me instructions on how to downgrade please.

Many thanks in advance!

Tech crew just received a new beta, we will test this one this week, will share info asap. 

I've update to Beta FW 3.0707.0
Yesterday I used this new version in Speedsurfing mode and I was not happy with the numbers I got
Display and upload on GP3S where the same, but not what I expected.
Some numbers
Fit/GP3S : 40,28kts (74,6kph) avg
GPX : 42,45kts (78,61kph) avg
Reverence is a Gyro with raw UBX logging : 41,67kts (77,19kph)

Posted logs : https://www.gps-speedsurfing.com/default.aspx?mnu=forum&forum=2&val=220858

Thnx for reporting, we also noticed this with the Vertix 2S and reported this back to Coros. The build for Apex provided much better data and brings the Coros devices back on the same level (and even a bit better) in comparison with the May software deployments. Please forward also the raw .UBX data and .FIT from the Vertix 2S to info@gps-speedsurfing.com , so we can share it with Coros.