Step 1: Check your credentials

1. Make sure the username and password entered in Site24x7 for vCenter or ESX are correct. 
2. Verify the credentials by logging into the vSphere Client with the same credentials used in Site24x7.

1. Log in to the vSphere Client using a privileged account, such as the root user or an administrative account.
2. Navigate to Administration > Single Sign-On > Users and Groups.
3. Verify if the credentials for the Site24x7 user account have expired, been locked, or are disabled.
   

Step 2: Investigate if the login is successful

If you can log in successfully using the credentials, but the error persists in Site24x7, any of the following issues may need to be addressed on your end. Proceed with the checks below:

1. Review event logs

1. Go to the Monitor tab in the vSphere Client, then click Events.
2. Filter the events to identify messages or warnings related to failed login attempts from the IP address of the Site24x7 On-Premise Poller.
3. Look for specific error codes or messages, such as invalid login, locked account, or session limits reached, originating from the IP address of the On-Premise Poller.
   

2. Verify session limits

1. In the vSphere Client, go to the Monitor tab and select Sessions. 
2. Review the number of active sessions. 
3. If the active sessions have exceeded the maximum concurrent session limit for vCenter or ESX, Site24x7 might not be able to create a new session with the resource.

To resolve the issue, terminate unnecessary sessions in the vSphere Client or increase the maximum concurrent session limit in vCenter and ESX to allow Site24x7 to establish a new session.

If the number of Site24x7 sessions exceeds 50, contact Site24x7 support for further analysis.

1. Navigate to Administration > Single Sign-On > Configuration > Identity Sources in the vSphere Client.
2. Check that the LDAP identity source settings are accurate and up to date.