ok,I finally tested with the new cable and I did exactly as you suggested with the settings.
I made sure the default rate was the same.
Then I restarted Audacity and for a bit it seemed to be working great. Then it hung up AGAIN saying the rate error.
I am at a loss. This didn’t happen until I updated my OS from Yosemite which I think was before El Cap.
I really appreciate your help but is there anything else I can do? Should I uninstall and reinstall Audacity?
Reinstalling Audacity won’t reset its settings. I doubt resetting settings will help. If you want to do it, quit Audacity and delete the audacity.cfg file as described here: http://manual.audacityteam.org/o/man/preferences.html#stored.
Are you switching away from Audacity before the problem comes back? If so, there is a small chance it might help if you right-click or CTRL-click over Audacity.app, choose Get Info, then enable the “Prevent App-Nap” box.
Are you restarting the Mac often enough? Have you tried Resetting the System Management Controller (SMC)? Resetting SMC is a little like a lower level reboot.
Gale
Ok, update!
First-your last points:
Are you switching away from Audacity before the problem comes back? If so, there is a small chance it might help if you right-click or CTRL-click over Audacity.app, choose Get Info, then enable the “Prevent App-Nap” box.
(Did this)
Are you restarting the Mac often enough? Have you tried Resetting the System Management Controller (SMC)? Resetting SMC is a little like a lower level reboot.
(I am restarting. Didn’t do reset-couldnt figure out)
NEW STUFF:
I installed the NEW update that just came out yesterday! I have yet to test and see if this will be the solution.
EL Cap was running some sort of encryption via “VAULT”? It may have been causing some issues according to a Mac guy I know. So we adjusted that.
New Hard drive: My computer was running SLOW. Kept getting the beach ball of death. So I found a great hard drive to replace mine that will make it run TEN times faster. I am hoping this will help too.
Next step: I will be running another test with the new Audacity in the next couple of days. I hope this is the fix we have ALL been needing.
Thanks again Gale for your help. It’s so appreciated
FileVault is not compatible with most audio recording applications. Neither is Fusion disk. I’m willing to bet this will fix all your problems with Audacity.
Is the case as strong as that? I don’t know, but the following links suggest disabling File Vault will improve performance or that File Vault is “not recommended” for audio and video apps, rather than not compatible:
https://discussions.apple.com/thread/3121622?start=0&tstart=0
http://avid.force.com/pkb/articles/en_US/Troubleshooting/Optimize-10-10#Disable_FileVault_protection
http://support.tcelectronic.com/entries/22065933-Mac-OS-X-General-audio-performance-optimization .
So I was reading that as for example prone to cause recording dropouts rather than prone to complete failures? But we’ll see.
And what about Windows disk encryption such as BitLocker? Same principle - not recommended for intensive apps? Spending a few minutes searching seems to suggest the performance impact on Windows is usually relatively minor, even on Hard Disk Drives.
Gale
It’s not as strong as that, no 
It’s just the way I put it to professionals recording 16+ channels.
If you only play stereo, you probably won’t notice it, unless you’re also doing bittorrent fi.
If you record 2 channels and expect low latency output at the same time, it might provoke hair loss. It’ll work one day and not the next.
I do know one person who uses FileVault and has no problem. But he only records one channel at a time and hardly uses his Mac for anything else. No internet, no wireless, no browser, no iCloud… The proverbial exception to the rule.
What helps, is disabling Spotlight indexing as that tends to kick in while recording in some programs that also create indexable files (text). In case of Audacity, I think the .aup file would get indexed. And since it changes constantly while recording, it sometimes get indexed again and again. Combined with full disk encryption, it can become very funny.
My simple solution for those needing encryption: create a .dmg or a separate disk partition that is encrypted and put your confidential files on it. Of course, don’t put the files you record on it. 
Also, excluding stuff from indexing doesn’t always work. Sometimes, Spotlight still indexes, but the results don’t show in a search, which is weird, to say the least.
Well, in spite of installing a new hard drive, new USB cable for mic, and updating Audacity, I am still getting an error. See attached picture.
I am sure its due to El Cap. This didn’t exist before I updated OS.
First, try disabling Bluetooth in system preferences. If that doesn’t help, go to the next step.
Try disabling Airplay and Airdrop. This seems to work in some cases on El Capitan. Copy this command and paste it into the Terminal:
sudo ifconfig awdl0 down
Airplay/Airdrop will be back after you restart your Mac.
This problem started in Yosemite, BTW, but was later fixed with an update from Apple. It’s not fixed on EC, yet.
Some questions:
/Library/Audio/Plug-Ins/HAL/Avid CoreAudio.plugin
Thanks as always for the steps and advice. I will do the fixes you mentioned.
Never have run protools.
Never installed any of those items you mentioned last
Reporting on your last ideas;
I did the tests at my computer without my mic plugged in.And audio engineer suggested I try it.
Reset SMC. Didn’t run into any issues.
Airplay and Airdrop options were hard to find and confusing. I typed in but only Airdrop showed up and I couldn’t click or unclick it.
I disabled bluetooth as well. Seemed to be fine.
You gave me a command to paste in the “terminal” but I am not comfortable doing that. I got a warning about loss of data.
So at this time, I will try to edit without my USB mic plugged in. This seems to be helping somehow with the issue.
And after all this time, if I do keep running into the issue, Ill just save and restart and continue edits. Its a pain, but until Audacity fixes this for El Cap, it will be a pain no matter what for me. Ill make the best of it
I want to thank you for your time and help over these past weeks. Please keep me posted on any new fixes. Best to you
I don’t think many people are having your issue as an intermittent problem.
When Audacity updates to the latest version of the PortAudio audio I/O library we use, it might help.
No one has mentioned “Audio to buffer” yet in Audacity’s Recording Preferences. Try it very low (0 or 10) and very high (200 or more). I can’t tell you what value might help, so experiment.
Gale
Thanks
I am not sure what the recording buffer you are referring to is, does, or where to find it
In “Preferences” in the “Recording” section.
Ok, Ill check it out.
Thanks again.