5) Read all the other support posts I can find about the -9934 error. Seems lots of people have the problem but no-one has fixed it :-(

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So selecting these settings should maintain the original format when transferring to the mac using ImageCapture. Which avoids the problems caused by the HEIC to JPG conversion.

1) As the photos all transfer OK using a different account, a different computer and AirDrop, this implies that the photos on the iPhone are all OK. So what is it about my account settings that is fouled up?

Update; I'm just found that there is an ImageCapture option called "Keep originals". Selecting this and it transfers all the photos in the original HEIC format with no problem.

1) checked disk space and permissions on the target folder. 45Gbyte of free disk space and Read/Write access so no problems there.

Update; just found that on the iPhone in Settings > Photos there is an option 'TRANSFER TO MAC OR PC'. There are 2 alternatives 'Automatic' or 'Keep Originals'. 'Automatic' might force a conversion to JPG. 'Keep Originals' should retain your original format selected in Settings > Camera > Formats. I've got 'High Efficiency' selected.

2) Why does ImageCapture on the mac pro transfer into JPG format whilst on the iMac it retains the HEIC format? I can't find an option setting for this anywhere.

So selecting these settings should maintain the original format when transferring to the mac using ImageCapture. Which avoids the problems caused by the HEIC to JPG conversion.

Transferring photos and video using ImageCapture v8.0 from iPhone 11 Pro running iOS v14.71 to a mac pro running OSX Big Sur v11.5.2 connected by a genuine apple USB cable. ImageCapture converts the photos from HEIC format to JPG in Pictures/Adriani11

Update; just found that on the iPhone in Settings > Photos there is an option 'TRANSFER TO MAC OR PC'. There are 2 alternatives 'Automatic' or 'Keep Originals'. 'Automatic' might force a conversion to JPG. 'Keep Originals' should retain your original format selected in Settings > Camera > Formats. I've got 'High Efficiency' selected.

This has occurred several times now. Previously I've worked round the problem by AirDropping the troublesome photos. But its getting tedious and needs fixing.