Urgent Vtiger Login Issue After Update -- 2

After updating my standard Vtiger installation, I'm unable to log in. Each time I enter my credentials, I'm redirected back to the login page. I need someone to troubleshoot this issue as soon as possible, so I can access my data again.

Ideal Skills:
- Vtiger CRM expertise
- Troubleshooting
- System Recovery

Experience:
- Prior experience with Vtiger installations
- Successful resolution of similar issues