How to Solve: Could not complete your request because Assertion in “E:\ Code\ 223110\ ProTools\ AAE\ Source\ AAX\ CFicAAXWidget.cpp”, line 851

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When you’re starting a fresh install of Pro Tools, running it after a new update, or booting up an older version, you might come across this error message:

Could not complete your request because Assertion in “E:\ Code\ 223110\ ProTools\ AAE\ Source\ AAX\ CFicAAXWidget.cpp”, line 851.

There are a few solutions to this problem you can try out. All of these solutions come from the official Avid Knowledge Base.

Solution 1: Hold “N” At Launch to Select a New Playback Engine

Your computer’s default playback engine might not be compatible with your copy of Pro Tools. So you’ll need to switch it to a different one. Here’s what you need to do:

  1. Launch Pro Tools
  2. During the loading screen, press and hold down the N key on your keyboard.
  3. Select a new playback engine and configure any other settings.
  4. Press OK to confirm.

Solution 2: Reset the Aggregate Device

An aggregate device is a virtual device or driver that combines the inputs and outputs of multiple physical devices into a single device. Mac computers have one built into the operating system.

On the other hand, Windows computers don’t have a native aggregate device. But a 3rd-party ASIO driver can do the job.

Windows:

  • If it’s not installed, download and install ASIO4ALL. Another similar driver might also work.

Note: While ASIO4ALL will work with Pro Tools in most instances, it isn’t officially supported or endorsed by Avid.

Mac:

Reset the Pro Tools Aggregate I/O in the Audio MIDI Setup (under “/Applications/Utilities/”)

  1. In the Finder, click Go > Utilities
  2. Double-click on Audio MIDI Setup
  3. Click Pro Tools Aggregate I/O
  4. Click the (-) button at the lower left of the window to remove the aggregate device

Solution 3: Delete or Rename the Pro Tools Preferences Folder

Your copy of Pro Tools might be struggling to find the Preferences folder. Here are the places to look as recommended by Avid:

Windows:

Find the preferences folder at this location: 

C:\Users\<username>\AppData\Roaming\Avid\Pro Tools

Mac:

Find the preferences folder at this location: 

Macintosh HD/Users/<username>/Library/Preferences/Avid/Pro Tools

Solution 4: Contact Avid Customer Support

At the end of the day, you can only do so much from reading articles like this or scouring old Reddit posts. If none of these other options work, try asking a professional at Avid’s Learn & Support page.