'Outlook Certificate' related errors are not common. However, they may occur when there is an issue with the security certificate, which is linked with your email server. It may also occur when Outlook detects or finds an invalid or untrusted security (SSL/TLS) certificate.
The error prevents Outlook from communicating with the mailbox server securely. Therefore, users may find it challenging to access mail items and send or receive new mail items.
In addition, when this error occurs, it can raise serious concerns about the authenticity and integrity of email communication. Without a valid certificate, any hacker can easily intercept, access, and read your confidential emails. Therefore, it is critical to resolve the 'Outlook Certificate’ error as quickly as possible and ensure the security of your email communication.
Common Reasons behind the 'Outlook Certificate' Error
There are several reasons that can lead to the 'Outlook Certificate' error. These include:
- Wrong or incorrect hostname
- Blocked SSL ports
- Use of wrong or insecure ports
- Incompatible or faulty add-ins
- Corrupt Outlook profile
- Damaged or corrupt Outlook PST file
- Outdated or wrong date and time in the system
- Expired or invalid security certificate
Solutions to Fix the 'Outlook Certificate' Error
Follow the below solutions to troubleshoot and resolve the Outlook Certificate error.
Solution 1: Check and Update the System’s Date and Time
The first step in resolving the 'Outlook Certificate' error is to check and update your system’s date and time. Follow these steps:
- Open Control Panel on your system and click on the System and Security
- Find and click on the Clock and Region option displayed in the left pane.
- Then, click Data and Time to open the settings.
- Check and verify that the following details are correct based on your specific region:
- If there is any discrepancy or date and time are incorrect, you can manually change it. To do so, click the Change date and time
- Then, edit/set the correct date and time. Please note that this requires administrator access.
- Once the date and time is updated on the system and it matches the date and time on the server, you can restart your system and check if error persists.
Solution 2: Verify the Security Certificate
Follow the given steps to validate the certificate trust chain and resolve the ‘Outlook Certificate’ error.
- In Microsoft Outlook, go to the File > Options and then click on Trust Center.
- Click on 'Trust Center Settings' and then choose 'Email Security'.
- Under Email Security, you will find 'Digital IDs (Certificates)'.
- Choose the certificate causing the error and click on 'View Certificate'. If you see the following error message on the screen, you can click the View Certificate button.
- In the certificate dialog box, check the Issued to
- The name should match with the mail server. If not, you must change it and then restart the system for the changes to take effect.
- Also, go to the 'Certification Path' tab and check if all the certificates in the chain are valid and not expired.
You can contact your email provider or administrator in case you encounter any issues. They can provide you with the correct and valid certificates.
Solution 3: Uninstall/Remove Add-Ins
Incompatible, faulty, or third-party add-ins can cause many issues in Outlook, including invalid certificate errors. You can follow the steps given below to find and disable the faulty add-ins from Outlook to resolve the issue:
- Close Outlook if running.
- Press Windows + R, type exe /safe, and click OK to start Outlook in safe mode.
- Once in safe mode, navigate to File > Options > Add-Ins.
- Find Manage Add-Ins and click the.. button.
- Clear the checkboxes beside all add-ins and click OK to disable them all.
- Once the add-ins are disabled, open Outlook. If caused by a faulty add-in, the error should not pop up.
If the error is resolved, activate one add-in at a time and restart Outlook. This will help you identify the faulty add-in. When found, remove it from your Outlook.
Solution 4: Update the Outgoing SMTP Ports
Many internet service providers have blocked SMTP port 25 due to spamming. So, if you are using port 25, you must update it to some other port supported by your mail server.
The steps to update the Outgoing SMTP port are as follows:
- Open MS Outlook and click on File > Info > Account Settings > Account Settings.
- Select your email account and click Change.
- Then, click on More Settings > Advanced.
- Here, you need to check the SMTP port and update it. Click OK to save the changes.
- Once done, restart Outlook to check if the error is resolved
Solution 5: Edit Outlook Settings
You can try to configure Outlook settings to trust the certificate. This can resolve the Outlook certificate error.
The steps are as follows:
- In Outlook, go to File > Options > Trust Center.
- Then, click on Trust Center Settings and then click Email Security.
- Click on the 'Settings' button, under 'Encrypted email'.
- Click on the 'Choose' button, listed under the 'Certificates and Algorithms' section.
- Then, select the certificate (if you have one) and click 'OK' to save the changes.
- Once done, reboot the system and start Outlook to check if the 'Outlook Certificate' error is resolved.
Solution 6: Repair Outlook PST File
A damaged, inconsistent, or corrupt Outlook data file (PST) can also cause issues in Outlook. You can try to repair your PST file to fix the error. For this, you can use the built-in SCANPST utility in Outlook. The steps are as follows:
- Close Outlook and open File Explorer on your system.
- Navigate to the MS Office installation directory.
- You will find the SCANPST.exe program file in it. Double-click on the file to launch the Inbox Repair tool.
- Then, click Browse and choose your PST file. The PST file is usually located at the following path: %localappdata%/Microsoft/Office
- Then, click Start. The tool will check the file for errors and inconsistencies.
- If found, click Repair. This will take a while to finish.
- After the repair, start Outlook and check if the error is resolved.
In case the SCANPST (Inbox Repair Tool) fails to repair the PST file or crashes/freezes during the repair process, you can use an advanced Outlook PST repair tool, such as Stellar Repair for Outlook to repair your PST file and restore all mail items in a new PST file. The software can repair large, severely corrupt, encrypted, and damaged PST files with complete integrity and precision. It can also export your mail items from PST files directly to Office 365 or live Exchange mailbox.
Solution 7: Create a New Outlook Profile
A corrupt or damaged Outlook profile can lead to a series of issues, including Outlook data file corruption, inaccessible mail folders, errors in sending or receiving emails, etc. Thus, you should try to create a new profile in Outlook and delete the old damaged profile. The steps are as follows:
- Close Outlook and open the Control Panel.
- Click on User Accounts > Mail and then click on Show Profiles.
- Click Add
- Then, type a name for the new profile and click OK.
- Continue following the on-screen instructions to configure your email under this new profile.
- After the new profile creation, remove your old profile.
- Restart Outlook.
After this, import the repaired PST file into your new profile and restore all your mail items.
You can also try the following quick tips to troubleshoot the error:
- Update your MS Outlook to the latest version to fix compatibility issues or bugs.
- Disable antivirus or firewall or install Outlook-aware software to avoid conflicts leading to errors in Outlook.
By resolving the 'Outlook Certificate' error, you can restore the security, reliability, and functionality of your email communication. Follow this guide to troubleshoot and fix the issue. Many times, the error occurs due to a damaged, oversized, or corrupt PST file. Use SCANPST to repair the PST file and resolve the error. If the tool fails to repair the PST file, use Stellar Repair for Outlook as a sure-shot solution that helps you recover all mail items from your corrupt or inaccessible PST file.