Fix An unknown error occurred (0x666D743F) in iTunes.

Solution summary

If you encounter errors while launching iTunes on your system, then follow the easy 4-step resolution.

Each step is accompanied by an indicative screenshot for ease of mirroring the action.

Read Detailed Solution

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Step 2

Open ‘QuickTime’
Double-click on the ‘QuickTime’ icon to open the QuickTime control panel dialog box and after that go to the ‘Audio’ tab.

Step 3

Modify the settings

Under the ‘Devices’ section, select the ‘Direct Sound’ option.

”Safe mode (waveOut only)” option is a radio button and we can”t unselect a radio button. We can select other option i.e. ”Direct Sound”. Please check the relative screenshot image to verify.

Step 4

Click ”OK”

Lastly, press the ”Apply” button then click on ‘OK’ button to save the changes.

We have successfully resolved the error message stating “The iTunes application could not be opened. An unknown error occurred (0x666D743F)”. Now, you can make sure that the iTunes application starts and functions smoothly.

We recommend that you fix errors related to iTunes by following the above-mentioned steps.

If you face any problems related to your computer, operating system, software applications or peripheral devices like printers, MP3 players, digital cameras etc., then call iYogi and we can fix it.

Note: If the Safe mode option is required for another application, then you can re-enable it once you have successfully opened iTunes.