When a specific user encounters an error that an administrator cannot replicate, the most effective troubleshooting technique is to "Login as" that user. This feature, which must be enabled in the organization's login policies, allows the administrator to see exactly what the user sees and experience the system through their specific profile, role, and sharing permissions22. This is vital for identifying issues related to Validation Rules, Field-Level Security, or Record-Triggered Flows that might only trigger under specific user contexts. Logging in as a system administrator (Option A) is ineffective because administrators often bypass certain restrictions that apply to standard users4. Asking for a password (Option D) is a major security violation and is never required in Salesforce5. By using the "Login as" feature, the admin can pinpoint whether the error is caused by the user's data input or a specific permission conflict assigned to their profile.