We often have this same issue, Mack. But that fact that your user says, "Unknown" is strange. I often see the error you shared, but the username is still tied to the schedule. In our cases it's usually because the user's credentials (ie. password) have changed since the schedule was created and the schedule attempted to run with the user's last known credentials and failed on the password. In most cases, it's just a matter of time for Cognos to receive an updated password from wherever your user credentials are stored (ours sometimes takes a few minutes to update). Ours aren't stored in Cognos but instead fed into Cognos from our single sign-on system (integrated with LDAP or Active Directory).
In your case, it sounds like it might not be the password at all and instead the entire user is missing from wherever you get your user credentials (configured manually in Cognos user-by-user vs integrated via LDAP or AD). Maybe person who created the schedule no longer has a user in your source of user credentials?
Either way, we often have schedules that are business sanctioned and generate reporting for public use vs schedules that users have for their own private content. Anything that is sanctioned for public use, we have a user name that we use as a service account with a never changing password. Then we use that user for scheduling things that are meant to be public and we can easily monitor when those schedules fail as opposed to whatever users created which we aren't public/business critical. It can be like chasing your tail trying to research failed schedules and prioritizing which ones need support vs those that don't (cause even a badly written report can cause a schedule to fail).
Whatever you decide, we change the owner of the schedule like this:

Good luck!
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Logan Whitaker
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Original Message:
Sent: Thu February 09, 2023 08:11 AM
From: Mack L
Subject: Schedules in Cognos fail throwing error
Hi,
A number of schedules have failed in a single day in our Cognos environment (Cognos 11.1.7) and when I checked the run history details, I found the following error:
"CM-REQ-4159 Content Manager returned an error in the response header. The error "cmAuthenticateFailed CM-CAM-4005 Unable to authenticate. Check your security directory server connection and confirm the credentials entered at login." can be found in the response SOAP header. CAF-WRN-2082 An error has occurred. Please contact your administrator. The complete error has been logged by CAF with SecureErrorID:2023-02-06-07:00:05.222-#7751 CM-REQ-4342 An error occurred with the client."
All the schedules that failed had 'Unknown' value for the 'Scheduled by' column in the Schedules tab of Admin Console. Also found that these schedules had been failing for a few past runs consecutively (5 runs). I don't have any information about who scheduled these. When I run a schedule ad-hoc using the 'run the schedule once feature', it runs successfully. Would like to know if I can resolve this issue by setting my credentials for the scheduled by property using,
Modify the schedule > use my credentials option of the schedule.
Since the error above indicates a change in credentials that has not been updated or renewed in the system, will the above solution, i.e., setting mine or anothers credentials instead of leaving it as 'Unavailable' work so that such failures do not happen again?
Regards,
Mack L
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Mack L
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