Airdrop not working between sonoma and catalina

I had the same issue on my MacBook Pro 16 that started well after my last Sonoma update. After trying the fix that had worked for others with no luck, I found that the issue was I had recently installed Wireshark's ChmodBPF.pkg to bypass starting Wireshark from the shell with "sudo." I double-checked and found the package performs the commands below.

chgrp admin /dev/bpf*
chmod g+rw /dev/bpf* 

Once I uninstalled the package and rebooted my laptop, there was no longer an issue with AirDrop of files from my phone to the Mac.

I hope this helps a few folks who have been scratching their heads when a solution that worked for everyone else didn't work for them. This was especially true for me because it had been at least a week after installing ChmodBPF that I tried to AirDrop a file.

Restart in Safe Mode. This will perform a Disk Repair, clear cache files and only load Apple Software, extensions and fonts. The boot up will be slow and can take some time - Normal.

Safe Mode will also eliminate Third Party Software, extensions and drivers from loading. It will only load the Minimum amount of Core Apple Processes to allow the the computer to function at a reduced Level of Performance 

Which is usually a indicator of some Third Party Security Software interfering in the Airdrop process

That would play into a previous suggestion to Remove such Software

Brian Davidson2 wrote:

Up front I'll admit I have not had time to troubleshoot. However, our family is finding that AirDrop either does not work or is very unreliable since the last round of IOS/Mac updates. With all devices on the latest major version (maybe not all on the latest update), Airdrop is not working. Either we get an "Airdrop failed" message or it simply times out.

If I find any solution or pattern once I troubleshoot, I'll post it back.

We have an iMac 2015 running Monterey and MacBook Pros running Ventura and Somona, plus iPhones on the latest iOS. Have been Airdropping a lot between them in all directions. So I think the software works. However when something stops working like this after applying an OS update, that usually indicates that something else (third party software or tool) installed no longer behaves properly under Sonoma and can interfere or conflict, causing the problems you see. This could be a matter of updating the third party software, or removing it.

You can run Etrecheck, a free tool that produces an anonymous report of your configuration. You should post that output here and people with many years experience will scrutinize it for such conflicts or problems. You can review the report before posting it here to verify that it contains no identifying info. Etrecheck is open source, by the way.

In addition to "cleaner" software and third party "Security" tools, as per PRP_53's excellent suggestion above, if you have VPNs or other network monitoring tools those can interfere. Look especially for any third party tool that has anything to do with networking, bluetooth, or WiFi, these can impact Airdrop.

What no one has mentioned.....it is possible Catalina is no longer a viable destination option because it is too old & is no longer a supported OS for Air Drop. Unfortunately Apple doesn't make it clear on the details in their documentation. I know several months ago I had a notice from Apple that some older systems would no longer support some features.

At the bottom of the following Apple article it mentions with older versions of macOS to make sure the Firewall is not blocking incoming connections, however, they don't specify exactly which older versions of macOS they are referring (only reference is Monterey or older, but how old...no one knows):

Use AirDrop on your Mac - Apple Support

Start by, reviewing all the elements of the article from Apple on using Airdrop

link below

Use AirDrop on your Mac to send files to devices near you

Excerpt from above

" AirDrop uses Bluetooth® and Wi-Fi to transfer items between devices. Most likely, you’ve already got Bluetooth and Wi-Fi enabled on your Mac. If you don’t, you’re asked to turn them on when you try to send an item. "

Any of the below should be removed as per Developers Instructions 

Disk Cleaner 

Third Party Security Software 

https://gist.github.com/joepie91/5a9909939e6ce7d09e29

Aside from what has already been suggested.

Both Devices must be on the same Network connection and in proximity to one another

Outside of above - no idea.

Though in my setup of 3 Apple Machines ranging from 2020 to 2022 and 2023 M1 / M2 Machines all running Sonoma 14.2.1 and iPhone running 17.2.1

Airdrop works 100% of the time

Then have a few suggestions ;

Start now and open an Apple Support Ticket as they are PAID  Apple Employees to deal will these types of issues . 

 Product Feedback - Apple and make it known to Apple regarding this ongoing issue 

Up front I'll admit I have not had time to troubleshoot. However, our family is finding that AirDrop either does not work or is very unreliable since the last round of IOS/Mac updates. With all devices on the latest major version (maybe not all on the latest update), Airdrop is not working. Either we get an "Airdrop failed" message or it simply times out.

If I find any solution or pattern once I troubleshoot, I'll post it back.