After Big Sur - Error 4302

David MacVicar Said:

"After Big Sur - Error 4302: Since upgrading to Big Sur, I continually get this error with my photos library now."

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Hi

What do you think happens when backblaze is trying to access files in the library to back them up - while photos is trying to access them to use the library?

Unless you disable backblaze while photos is open, you can expect problems.

Can you also confirm the external drive is correctly prepared?

It must be formatted APFS or MacOS extended (journaled), and not be (or have been) used for time machine. It must have the 'ignore ownership" checkbox ticked. It should not be on a memory stick, SD or similar. It stands to reason that if you want any sort of reasonable performance it should be a fast drive with a fast connection.

See

https://support.apple.com/en-gb/HT201517

How is the external hard drive connected to your Mac? Your external hard drive should have a wired connected (not a NAS), it must not have been used by Time Machine or other backup service, the file system format should be MacOS Extended (Journaled). And the external volume should always be mounted, when you log into your user account.

Move your Photos library to save space on your Mac - Apple Support

Is your Backblaze installation thoroughly up to date?

I've had Photos libraries on both internal and local external drives and backed up by Backblaze on Mojave, Catalina, and Big Sur without ever seeing an error 4302 or anything similar. (That's the same iCloud Photos library with 84K photos and 1K videos across several Macs.)

Is it also the correct format?

Should be good enough. Speed also shouldnt cause that sort of issue as long as it's not stupidly slow. I assume the connection is USB3?

So - I'm out of ideas.

All I can think of is to keep Backblaze permanently disabled for a few days to see if it makes any difference.

David MacVicar Said:

"Yep! I did that when it first happened - thanks :D"

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👍

You are welcome.

Well done on your par. Providing feedback will help many for sure.