Rhino Sync plugin read-only file system error

Plug Ins Rhino Sync
1

Hi,

I just installed the Rhino Sync plugin on my Mac, and I am running into a sequence of issues every time I try to connect to a model shared with me on Google Drive.

Initially, I am able to log into Google Drive and choose the shared file. Rhino Sync then redirects me from Chrome back to Rhino 8, but it gives me an error saying: “Read-only file system: ‘/Rhino.Sync’”. I realized that the plugin’s code appears to be attempting to write to the absolute root directory of the Mac (/Rhino.Sync) rather than the user directory (~/Rhino.Sync), which modern macOS blocks for security.

To try and fix this, I changed every file inside the package directory ~/Library/Application Support/McNeel/Rhinoceros/packages/8.0/RhinoSync to have read and write permissions, tried sharing the file to a different Google account, and even tried older versions of the plugin, but nothing worked. I was eventually able to temporarily bypass this read-only error by creating a virtual symbolic link at the root level (using synthetic.conf) to map /Rhino.Sync to a writable directory I created at /Users/Shared/Rhino.Sync.

However, while this successfully cleared the read-only error, it led to a new issue. Now, when the plugin attempts to connect to the shared file, it immediately crashes and throws this exception: “Object reference not set to an instance of an object.”

I have confirmed that I have full “Editor” access to the file on Google Drive, so it doesn’t appear to be a cloud permission issue. It seems the plugin is failing to initialize its required subdirectories or background files within that new path. For context, I tried switching to a Windows virtual machine, and the plugin works just fine there.

I have attached screenshots of both errors for your reference. Please let me know if you have any idea what is causing this sequence of errors and if there is a patch or specific workaround I should use for macOS.

Thank you!

Screenshot 2026-08-29 at 7.08.10 PM
Screenshot 2026-08-29 at 7.08.10 PM1920×1117 237 KB

Screenshot 2026-08-29 at 7.34.00 PM
Screenshot 2026-08-29 at 7.34.00 PM1920×1111 244 KB

2

Update on troubleshooting:

The connection to Google Drive seems to not be the issue. I tried to load the model using the “Network Disk” option and I got the same result.

3

Another quick update:

I believe the workaround I attempted would function perfectly if I could map it to the exact directory hardcoded within the plugin’s DLL. I suspect that forcing the plugin to use a custom directory to bypass the read-only error is what triggers the new exception; it is likely looking for its background data in its original intended path rather than the workaround directory.

I have already tried routing the virtual link to two directories that would make the most sense as macOS equivalents to where I found the cache in the Windows version: “~/Library/Application Support/” and “~/Users/Shared/”, but neither resolved the secondary crash. I’m thinking of decompiling the DLL to figure out the hardcoded directory.

4

Update:

I had my friend try the plugin on his Mac running macOS Sequoia and the plugin worked just fine. I am running macOS Tahoe which might be causing the issue. I also tried to reinstalling Rhino 8 and that didn’t work.

5

Solution directly from developer:

  1. Open terminal and run: launchctl setenv HOME “$HOME”
  2. Then run Rhino 8 from terminal using (adjust based on your Rhino 8 directory): “/Applications/Rhino 8.app/Contents/MacOS/Rhinoceros”