Sigma 150-600 Contemporary won't communicate properly with R5 and R6 since firmware upgrade

[markphoto]

I'm using the Sigma 150-600 Contemporary with an EF-R adapter on my R5 and R6.  It worked fine, until I upgraded the camera firmware to the latest version.  Since then, I get an Error 01, "Communications between the devices is faulty.  Check the camera, lens, or mount adapter contacts". 

I have tried cleaning all the contracts with isopropyl alcohol.

Has anybody encountered this problem?  Will upgrading the lens firmware solve the problem?  I would have to purchase the lens dock to do this.

[Tronhard]

Given you use Canon adapters, I would recommend checking that status of the lens own firmware version.  While Sigma clearly states that they do not guarantee that their lenses perform with R-series bodies, having the latest firmware installed on the lens is always a good move.   I have the latest firmware on my Sigma lenses and upgraded to 1.6.0 on the R5 and R6 bodies with no issues.

[markphoto]

Saving the settings to an SD card and then resetting the basic and custom settings seems to have worked.  I haven’t tried it in the field yet, but test shots are not getting the communication error anymore.  Reloading the settings didn’t undo the fix.  

this may be a problem only with the R5 and Control Ring adapter, as the lens seems to be good on my R6 with the EF-R adapter now.  Or the Gods are done toying with me.

[markphoto]

I purchased the Sigma USB Dock for EF lenses. And downloaded their software. It to,d me the firmware was already the latest version. However, I reset the lens to the defaults, which rewrote the firmware. It’s working with my R5 now. I’m not sure if something in the lens inadvertently got changed or the firmware was corrupted when my first EF-RF Control Ring adapter got a crack in the mounting hardware and had to be replaced. In any event, it now seems to be working, so I’ll have to try it out in the field.

[Tronhard]

Good to know that you are making progress.  I don't recall you mentioning the event that caused the crack in the adapter - that was definitely a significant factor we would take into account.

I hope your testing works out well with both.