Issue Invalid Certificate Error on Mac

Invalid Certificate Error on Mac

Before Mac users are taken to any website, the macOS makes sure that the page is safe by checking that if that specific website has a valid certificate. If the certificate has expired or is outright invalid, users will see a warning screen asking them to decide whether they want to continue to the potentially unsafe page, whether to inspect the certificate manually, or just close the website. It is perfectly normal to see such a warning from time to time while browsing the net. If the frequency at which the Invalid Certificate error appears starts to reach abnormal levels, then it might be a good idea to check if everything is adjusted properly on your system. 

Clear the browser cache

Start by clearing the cache files created by your Web browser. Doing so is oftentimes the easiest and fastest way to fix any browser-related problems. In this case, the website causing the Invalid Certificate error might have made changes to its domains leading to compatibility issues between the saved cache files used by the browser and the current state of the pages. 

  1. Open Safari.
  2. Go to the 'Preferences' menu.
  3. Select the 'Advanced' tab.
  4. Enable the 'Develop' menu.
  5. Now, go to the newly available 'Develop' menu.
  6. Choose the 'Empty Caches' option.

Use correct date and time formats

Discrepancies between the date and time format used on your Mac system and the format on Apple's server must be in sync or risk encountering numerous issues. To make sure that you are using the correct format, follow the steps:

  1. Go to the Apple menu.
  2. Open 'System Preferences.'
  3. Select 'Date & Time.'
  4. See if the checkbox next to the 'Set date and time automatically' option has been selected. 
  5. Make sure that the correct server corresponding to your geolocation is selected.
  6. Close 'System Preferences,' wait a couple of minutes, and try to open the site triggering the Invalid Certificate error.

Adjusting the certificates on your Mac

If the Invalid Certificate error persists, then you can try to manually adjust the certificate settings on your device. 

  1. Open the Applications folder.
  2. Go to 'Utilities.'
  3. Launch 'Keychain Access.'.
  4. Select the login keychain.
  5. Look at the bottom of the sidebar and select 'Certificates.'

Once here, inspect the list of displayed site certificates. The ones marked with a green tick use the default settings and are valid. Instead, look for any that show a red 'X' when you click on them. If any such certificates are present, right-click them, and choose 'Delete' from the available options. The next time the deleted certificate is needed, it will get a fresh download.

Edit certificates with custom settings

If any certificates in the displayed list have a white cross surrounded by a blue circle in their icon, that means that they are using custom settings. To manually adjust them, do the following:

  1. Double-click the certificate to open its settings.
  2. Locate 'Trust' and click on the arrow next to it.
  3. Look through the options available via the dropdown menus and adjust them according to your needs.
  4. Close the window. 
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