16.5.1 (c) Bluetooth Failure on iPhone11 Pro

iPhone 14 user here. After the security update, my wireless CarPlay (BMW iDrive 8) stopped working. I can't connect via bluetooth to car no matter what I try. However, my bluetooth Bose headphones and my Fitbit are working as expected. As mentioned by someone, it is not an issue impacting all but individuals under specific scenarios. It may not be a failed update but it is a buggy security update that is causing bluetooth recognition issues. I've tried looking into settings but nothing stands out to be changed that would have impacted my CarPlay issues. Hopefully someone solves it soon (likely Apple as the issue is impacting many third party devices)

I had deleted the connection on both car and phone. I turned on & off the my car “restarted” it, rolled back and paired it again with no issues.

Yes, on a 12 mini. Reboot of the phone allows connection, but within 10 minutes the audio breaks up, and phone will not reconnect without another reboot. Tried 3 devices and multiple apps. AirPods Pro show up when the case is opened, but won't connect. No problem with speaker, only Bluetooth/h1-2 audio devices. Showed up immediately after update.

When I rolled back I was able to connect with no issues

I think the update caused my iPhone 13 to break my fitBit (suddenly won’t hold a charge or even show the time) and Bluetooth headphones (disconnects after about 15 seconds). It looks as if the software in my Bluetooth devices aren’t compatible with 16.5.1(c) 😖 I hope Apple fixes the problem soon.

Removal of the update did not fix the issue. Phone connects, but audio breaks up afterwards. If I disconnect, I am unable to reconnect again until a phone reboot

Updating iOS on your iPhone should not change your personal details. iOS updates primarily focus on improving system performance, introducing new features, fixing bugs, and enhancing security. They are designed to preserve your personal data, settings, and information intact.

During an iOS update, your device's operating system is upgraded, but your personal data, such as contacts, photos, messages, and other information, should remain unchanged. However, it's always a good practice to perform a backup of your device before any major update to ensure that your data is safely stored.

It's important to note that while an iOS update itself should not alter personal details, it's possible that certain features or settings may be adjusted or improved with the update. In such cases, you may need to review and adjust specific settings to match your preferences after the update.

Always make sure to read and understand the update details provided by Apple before proceeding with an iOS update, and follow best practices such as backing up your device to minimize any potential risks or complications.

If the issues you mentioned are indeed caused by iOS, it's likely that numerous users who have upgraded to iOS 16.4.1 (a) or 16.5 or 16.5.1 or 16.5.1 (c) are experiencing similar problems. However, in order for the community on this forum to provide helpful responses, it would be beneficial for you to specify the nature of the issue you are encountering. Without this information, it may be difficult for others to address your concern effectively.

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.

The same here, door lock and insurance dongel don't connect anymore!

13 mini.

Manually it works with the lock but no connection is established in the background. Watch is running. However, the dongle from the insurance only goes automatically to Connect in the background (DriveWell) Is otherwise not displayed on devices.

I have an iPhone SE 2nd gen with the most updated iOS. I have an iMac with Ventura. After the security update, the iMac doesn't show up in the list of Bluetooth devices on my phone, but all the others do. So frustrating!

same here with mi Bluetooth connectivity to my car. Would not pair (I’ve had the car for 2 years with no issues before). I deleted the connections on both sides and now I get the unsuccessful error. I need the hands free option in car. Please revert any fixes

I am certain that iOS 16.5.1 (c) has not affected your Bluetooth.

However, you can remove it if you want. See the pic below which is self-explanatory

Rolling back to remove the update is extremely strong evidence that the update was not the cause of problems. You got hit by coincidence.

I have a 13 mini. Phone support was of no help at all--spent 2 hours with them disconnecting etc. etc. Not sure what's next--if I go to a store appointment, what can they do? Anything?

So after playing with it a bit, the iMac is showing up on the phone, but when I click on it, it says 'Pairing Unsuccessful - the iMac is not supported.' Argh. It was fine a few days ago!

I rolled things back and I'm still stuck. What a mess!