I think this might be useful if you use M4L and had issues after installing macOS 10.13 / High Sierra. The below note is from Ableton Support:
Regarding the issue with High Sierra and Max for Live we have found a workaround that seems to work for all affected users so far.
Should you consider following this instructions please understand that you try this at your at your own risk.
You would have to copy some files manually into the Live.app.
To do so please follow these instructions:
- Make sure Live 9.7.4 64-bit and Max 7.3.4 are installed in your Applications folder and are not running
- Download this file.
- Unzip it to a folder and leave that finder window open
- Open a new finder window and go to your Applications folder
- Right click on the Live.app and select Show Package Contents
- Place the Frameworks folder that you unpacked before in the Contents folder of the Live.app
As soon as you load a Max device you'd still be asked for your password, but the device should load afterwards.
Please note that this workaround is not a final solution and doesn't substitute doing a proper upgrade to Live 9.7.5 when it is released later in October. Further it might not work for customers with a 32-bit version of Live.