Multi Monitor Wallpaper: macOS 14 Sonoma flashing and disk space issues

[Alexander Clifton-Melhuish]

Hi everyone, longtime and very satisfied user of Multi Monitor Wallpaper here!

I'm wondering whether there is a pending MMW update for macOS 14 Sonoma? I've experienced two issues since upgrading to Sonoma:

1. Occasionally, wallpaper on one screen will repeatedly 'flash' (as though it is reloading multiple times).

AFAIK it is only one monitor at a time, but I rarely use more than two screens so it may only effect e.g. external monitors. I haven't identified any pattern to when these episodes occur, and they usually resolve themselves after a short period (max. 1 minute?).

2. I've identified a huge folder (currently 39.4GB!) where macOS is caching multiple copies of wallpaper images.

No doubt this path contains unique values, but on my system is appears at: 

/private/var/folders/f6/76gsg51x2qd5jzg9h26hn8tm0000gn/C/com.apple.wallpaper.caches/extension-com.apple.wallpaper.extension.image

Each copy has a  filename constructed as:

[64-digit hex number]-[width in pixels]-0-[16-digit hex number].png

I dumped MD5 hashes into a file and determined that there are up to 83 copies of the same image in this folder. Maybe this is a macOS bug, or maybe it's an unexpected result of how Sonoma now deals with wallpaper images in combination with the way that MMW works?

If I can help with diagnosis/debugging of either issue, then please let me know how and I'll be happy to help.

Thanks,

Alex

[Confused Vorlon]

Hi Alex,

thanks for reporting this.

At the moment, I haven't updated to Sonoma as I'm in the middle of a large project which requires me to stay on Ventura.
That's going to be more or less my sole focus for the next few months.

At some point, I will update, and MMW will get some love.

There has clearly been a bunch of change in the way Apple is handling wallpapers to support the new video wallpapers. I don't know how that has manifested in practice.

No idea what is going on with the flashing I'm afraid. You could try turning off the options in 'Auto Apply' under settings. It's just about possible that these were being triggered multiple times...

The /private/var/folders is generally used for temporary cache files. As such, the OS _should_ deal with clearing that out as needed.
Obviously these are being created by the system wallpaper extension - so I don't have much insight into what it is doing.

Possibly re-caching every time the wallpaper is re-set??? (see auto-apply above)

At least in theory, files in caches should be cleared out by the system if it needs the space, so you should be able to ignore them and assume they'll be deleted if necessary...

thanks again for the report & investigation.

Rob

[Lantz Warrick]

I'm also getting the flashing issue on macOS 15 Sequoia.  I don't know if I'm getting the bloating cache issue as well (haven't checked the cache files).

Am following to see if there are any solutions...

Thanks