What version is your ArcGIS Server?
If it is ver. 10.5, then it would not accept a PRVC/ECP file of 10.1-10.4.x.
You need to authorize ArcGIS Server 10.5 with a fresh license code/ECP file generated from ver.10.5 only.
I installed ArcGIS for Server 10.4.1 and am using an ECP code.
Thank you for the details.
Ensure the license hasn't expired. And the ECP file should have been generated from ArcGIS Server 10.1 or later
Did you allocate it on another machine (i.e. are you moving to a new machine). For example, it you had 10.3.x installed on another machine, and starting fresh with 10.4.1 on a new machine, you need to deauthorize it first. You can only authorize ArcGIS Server once. Check out your myesri page to see if the authorization still says 1/1 or if it is 0/1.
I ran an ArcGIS for Server Workgroup 10.4.1 and used an ECP code for ArcGIS 10.5 to Authorize..
Not sure if an ECP file of ArcGIS Enterprise 10.5 will work for 10.4.1.
Earlier the ECP file for 10.1-10.4.x were similar, but in 10.5 it has changed.
Please check with your local Esri Tech Support to work closely on this issue.
Thanks so much@ Poddar