Compressor 4.1 – Failed: 3x HOST [computer name] Error: className is null!

[Martyn Greswolde]

I have almost exactly the same issue but I do not have any host listed in my error report-

I had been having issues with Qmaster before the new FCPx suite so I uninstalled both Qmaster and its pref pane (I have no idea if this is related to the issue or not)

Greswolde Photography
http://www.greswolde.com

I know little but I learn quickly!

[Max Tannone]

Thanks Martyn. I do not, nor ever had, Qmaster and its preferences pane installed. (I briefly tried experimenting with Qmaster using the old compressor, but don’t remember having a preferences pane in system prefs or anything like that.) I may have just contradicted myself – but I definitely didn’t separately install Qmaster with the old Compressor.

Regardless, it may be totally unrelated.

[James Cude]

That’s strange. Which setting presets are you using? If you are modifying them, how?

[Max Tannone]

The two different encodes I’ve tried were using the following settings:

1280×720 h264 MOV, 3000kbps, 128kbps AAC

and

960×540 h264 mp4, 750lbps, 128kbps AAC

Both are custom settings that I made.

[James Cude]

Could you possibly still have remnants of the old Compressor and Qmaster somewhere causing problems? If these files still exist, try trashing them:

/Library/Frameworks/Compressor.framework
/Library/Frameworks/QMaseter.framework
/Library/Frameworks/AECore.framework
/Library/Application Support/Apple Qmaster/

[Max Tannone]

Thanks James.

I did find: /Library/Application Support/Apple Qmaster/

I deleted the folder.

However, before I did that, I tried running Compressor again, and got this message:

I got the same message after deleting that Qmaster folder as well.

Then, I deleted Compressor.app and re-downloaded from the App Store. Same message. Very confused.

[Martyn Greswolde]

I found all of the files you listed and deleted them and I get the same error message as the OP.

I have tried my own compressor settings as well as the apple shipped presets and all return the same error (although slightly different to the OP’s)

Fresh Mint Films

I know little but I learn quickly!

[James Cude]

Do you have the same problem with completely different clips and one of the built-in transcode presets?

[Martyn Greswolde]

Yep, different clips, as many presets as I can through at it, same result (apart from now I just get the above error.

Fresh Mint Films

I know little but I learn quickly!

[James Cude]

When I couldn’t submit in pervious versions, I’d remove ~/Library/Application Support/Apple Qmaster, then restart. This would fix most things. In 4.1, it looks like they are using ~/Library/Application Support/Compressor, so try removing that and restarting. Just be aware that your custom settings are stored there as well, so be sure to copy them before you delete the folder if you want to keep them.