Error Pro Tools could not set sample rate to specified value

[vmc.mariana]

Hi, so I'm getting this error:
"Could not complete your request because Pro Tools could not set sample rate to specified value".

I have searched forums for a solution but still couldn't find it, so I was hoping somebody could shed a new light on this. This of course interferes with my job and the anxiety is spiking through the roof.

These are my specs:
Pro Tools Version 12.7.1
Hardware Scarlett 18i20
iMac (Retina 4K 21.5-inch, Late 2015)
Processor 3,3 GHz Intel Core i7
Memory 16 GB 1867 MHz DDR3

I believe I know what caused the problem. Today I opened Pro Tools for a few corrections on a MIDI track and that was fine. Then, later on, I opened Logic Pro for a different project and the monitors started clicking. I turned the hardware off and on again and it worked normally. Skip to a few hours ago and now I can't open any session, new or old, because of this issue. So I think I know the cause, but not how to solve it.

I've already tried a lot of things (that haven't worked) like:
- Resetting the computer;
- When starting Pro Tools, pressing "N" to change the hardware;
- Trashing Pro Tools Preferences;
- Removing the hardware from the Logic Preferences;
- Changing computer main sound output from Scarlett to the built-in output (though it still functions normally with the external hardware).


There was one thing that worked temporarily. I turned the hardware off and opened a session with the built-in output, which worked twice and stopped working once again.

I really need help, thanks in advance and sorry for the long post.

[musicman691]

You're missing one important thing in your specs - what exact OSX are you running?

Questions:
Do you start your audio interface before starting the computer?
When do you get the error in question? It indicates PT isn't seeing the interface for some reason. Are you starting PT first and then the session? Try that. Also try starting PT first and then create a new session - see if you get the error message.

Try reloading the drivers for the audio interface.

Not knowing exactly how the interface is connected to your computer change the interface cable - with everything powered off of course.

What exactly do you mean by 'resetting the computer'? There's a couple of different things that term could apply to.

Sometimes when I get a problem that all the logical steps don't work I do this:
Shut everything down. Unplug the computer from the AC mains. Count to 30. Replugin the computer. Start up all peripherals. Start up the computer. That usually fixes the strangest of problems.

[Darryl Ramm]

I suspect you may be having problems caused by allowing you Mac to suspend/sleep with the interface connected. You need to set the iNac to never sleep in Energy Saver preferences. If this is an issue, just rebooting the Mac (not interface) should fix it.