Maxwell 4 crash after update to Catalina

Hi folks!

We are experiencing critical crash with Maxwell plugin after updating to Catalina. It always shows this error message when starting Rhino

and all Maxwell commands just cause the crash of whole Rhino. I know there have been some troubles with catalina before…We use R5 together with Maxwell 4. Any ideas?


Hi Petr - for issues with Maxwell, you will have to contact support at Next Limit.

Yep, I posted it in maxwell forum as well. Anyway, somehow might have some experience here as well :slight_smile:

I agree contacting the NextLimit folks is the right way to go. That said…

I’ll bet this is only happening on new installations of the plugin, am I correct?

My guess is that is a code-signing or Notarization issue. I’m guessing macOS’s Gatekeeper has marked that file with some extended attributes or it does not have hardened runtime entitlements. If it’s the former - a code-signing error (which is the most likely) - you might work around it by doing the following:

  1. Figure out the path to libmwdotnet_native.dylib. Launch and run the following command: cd / and press enter. Next run the following command: find . -name libmwdotnet_native.dylib -type f and wait. You might get some Operation not permitted results, but eventually, it should print the path to libmwdotnet_native.dylib. Copy that path.
  2. In, remove the extended attribute on that file with the following command:
    xattr -d <full/path/to/libmwdotnet_native.dylib>

Really, this is not a good workaround though. Code-signing and/or Notarization for the plugin will need to be fixed. Bummer as that stuff is a real pain.

Hi @dan and thank you for your response.

I am not sure by this, we were running MX4 on Mojave without any errors, then after updating to Catalina, error occurred.

Anyway, thanks a lot for the workaround, I will try it out, since I have no reply from NextLimit guys yet.


Hi @dan ,
I wasn´t successful with the workaround (100% sure that its my mistake), but I got answer from NextLimit guys:

Try to download the software from your portal because now it is signed to work for Cataline. Apple changed the software politics so we needed to sign the software again to work with Catalina.



Thanks, that’s great news @petumatr! I’m glad the folks at Maxwell managed to Notarize it.

Hey there again @dan ,

so it was a bit ahead of time, it seems they didn´t update MX4 for Rhino 5.

Some users have been reporting this issue with some frequency lately. I wish NextLimit had notarized their Rhino 5 for Mac plugin, but they did not. The post above is accurate and it is a viable workaround (I just tested it), but it does presume you know something about Terminal. Hopefully these instructions are more user-friendly:

  1. Launch Rhino 5 for Mac 5.5.5 (NextLimit has told users they need to roll-back to 5.5.3; you do not need to roll-back to 5.5.3)

  2. Run the .macrhi that Maxwell provides. The installer should work and report that it worked. If you are presented with the error message(s) about libmwdotnet_native.dylib being damaged, do NOT click Move to Trash. Click though and ignore all those warnings.

  3. Quit Rhino 5 for Mac completely. It should not be running.

  4. Launch macOS’s You can do this by pressing Command+space to launch the Spotlight app and typing Terminal and pressing enter.

  5. At the $ prompt, type the following command:

cd ~/Library/Application\ Support/McNeel/Rhinoceros/MacPlugIns/maxwell_rhino.rhp/

…and press enter. The above command changes to the Maxwell plugin folder. Next, at the prompt type:

xattr -d libmwdotnet_native.dylib

…and press enter. The above command removes the quarantine extended attribute that is causing the error for that file. Next, at the prompt type:

xattr -d libmxdotnet_native.dylib
and press enter.

  1. Quit the Terminal Application.

  2. Launch Rhino 5 for Mac. Maxwell should load and work as expected.

Hi @Dan, thank you! I will give it a try and come back to you :slight_smile: NextLimit has just ignored all over questions and complains so far…

edit: wow, it works @Dan, finally solved! Thank you!

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