Useful to know,
@bluetti can you advise when this will be fixed for Apple/ IOS devices ?
@Chorlton Did you also experience a crash when updating the firmware on your Apple device? If so, please let me know the details. I will give feedback to the relevant R&D engineers
Hi,
Thanks for your reply, having seen the other people’s experience I didn’t want to risk the upgrade using an Apple device. Sorry I can’t help you further. I was interested in when it had been resolved.
Has this issue been fixed? I purchased a ac200max last week and ran into the same issue today. 034 communication failure after firmware update. My ac200max is bricked. I am using the IOS app version 2.1.2. I thought this issue was fixed i the later versions of the app.
Not sure what my options are. Any help will be appreciated.
My first attempt to update BMS via the iOS app failed just like yours. I cleared the cache, this is a option inside the Bluetti app itself, and then started the BMS upgrade again. This time I saw progress right away when it switched to the “BMS upgrade in progress” screen. It only took a minute or so and the 034 alarm on the AC200MAX was cleared and has not occurred again.
Be sure to keep your phone from going to sleep or switching away from the Bluetti app during the short upgrade process.
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Thank you very much. That worked after a few tries.
I just went ahead and upgraded my BMS as well. I used your tip of clearing the apps cache before attempting the upgrade. Then, I just went ahead and did it. Took about 40 seconds for me using a iPhone 13 to be completed. 
Did mine a few days ago using iPhone on home internet, all fine.
This tip worked for me as well. Took me 2 attempts but it worked.
Thank you. 