• Permission errors with the destination folder (e.g. not writable by the current user).
• Conversion failures if you have the iPhone set to export images in “compatible” formats rather than their originals¹
• Unsupported image formats (e.g. HEIC) on very old versions of macOS (macOS 10.12 Sierra and earlier).
• The destination folder not existing.
• Etc.

Basically it seems like this “-9934” error is a catch-all for any kind of I/O error. Good job, Apple, in providing useful information to your users.

But add to the aforementioned list one other possibility, that I didn’t see mentioned anywhere: the destination volume is full.

I’ve been hitting this error message in Image Capture sporadically for months and been baffled by it – especially since it seemed to occur for seemingly random sets of images and videos, that were sometimes consistent between attempts and sometimes changed unpredictably. Which is of course the result of the destination volume being perpetually close to full but varying slightly over time as random bits & pieces are added or removed from it.

It’s especially tricky because the destination volume won’t typically show as actually full, in the Finder – it could have virtually any amount of space left, even hundreds of gigabytes, because the particular image or video that hits the limit could be huge, and Image Capture either tries to pre-allocate the entire file’s space up front (failing immediately if there’s insufficient space) or retroactively zeroes out the file if it encounters a write error. Either way, it leaves a bunch of zero-byte files (the failed transfers) behind, rather than incompletely-written ones, further hiding the fact that it ran out out of disk space.

1. Please don’t ever do that. It means transcoding your original images from DNG or HEIC into JPEGs, increasing their file size and/or reducing their quality in the process. Don’t do it. DNG and HEIC are old formats that are widely supported – not just on Apple devices, but Windows as well (and probably most Linux distros). ↩︎