Outlook continually prompts for password when connecting to Microsoft 365

Symptoms

• Outlook repeatedly prompts for a password while showing "trying to connect..."
• Cancelling the prompt shows "The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action."
• The prompt reappears even after entering correct Microsoft 365 credentials

Environment / applicability

Windows Outlook Outlook 2013 / Outlook 2016 (older builds)

Outlook (Outlook 2013 (older builds), pre-update Outlook profiles) — lifecycle: unknown

Diagnosis

1. Check the Logon network security setting: Control Panel > Mail > Show Profiles > select profile > Properties > E-mail Accounts > select account > Change > More Settings > Security tab. Check the Logon network security value.

   Expected: If the value is anything other than Anonymous Authentication, this is the likely cause.

Root cause

This occurs when the Logon network security setting on the Security tab of the Microsoft Exchange dialog box (in the account's More Settings) is set to a value other than Anonymous Authentication. Outlook 2016 and recent Outlook 2013 builds removed this setting and are not affected.

Resolution

1. Run the built-in connectivity diagnostic (newer Outlook builds): In Outlook, select "Diag: Outlook keeps asking for my password" to run the automated connectivity diagnostic and apply its suggested fix.

   Expected: The diagnostic identifies and offers to fix the specific cause of the repeated prompt.

2. Set Logon network security to Anonymous Authentication (older Outlook builds): Exit Outlook. Control Panel > Mail > Show Profiles > select profile > Properties > E-mail Accounts > select account > Change > More Settings > Security tab > set Logon network security to Anonymous Authentication > OK > Next > Finish > Close.

   Expected: Outlook connects without repeatedly prompting for credentials.

   Warning: Applies to older Outlook 2013 builds and earlier; Outlook 2016 and recent 2013 builds no longer expose this setting.

Verification

1. Restart Outlook and confirm it connects to the Microsoft 365 mailbox without a repeated credential prompt.

Rollback

Changing Logon network security back to its prior value reverses the change; this is a per-profile client setting with no server-side or tenant-wide effect.

1. Repeat the Security-tab navigation and set Logon network security back to its original value.

Risk

Risk level: Low · Requires admin: No

References

• Outlook continually prompts for password when you try to connect to Microsoft 365 — Microsoft

Record metadata

ID

fx-outlook-0001

Created

2026-08-16T00:00:00Z

Updated

2026-08-16T00:00:00Z

Freshness

current