# Failed to connect to Exchange O365-certificate

When you run the Synctool or a custom PowerShell script, you see the following error:

> Failed to connect to Exchange O365-certificate: Connecting to remote server outlook.office365.com failed with the following error message. For more information, see the About Remote Troubleshooting Help topic.

## Cause

You are using an outdated version of the **ExchangeOnlineManagement** PowerShell module, or the module is not installed at all.

## Solution

Update or install the **ExchangeOnlineManagement** PowerShell module (version 3) by following these steps:

1. Run PowerShell as Administrator.
2. To update the existing module, run the following command:
   
   ```powershell
   Update-Module -Name ExchangeOnlineManagement
   ```
3. To install the module, run the following command:
   
   ```powershell
   Install-Module -Name ExchangeOnlineManagement
   ```

Updated on 2026-06-18