As it turns out, there are several different potential culprits that might lead to the apparition of the “Configuration could not be verified” error. Here’s a short list:
Method 1: Ensuring that the Account Credentials are Correct
Before you explore any other potential fixes, you need to make sure that you are using the correct account credentials. It could be that the error message is simply signaling that the email or password you’re using is incorrect. Fortunately, there’s one way to test out this theory – Simply attempt to use the same account directly from your browser and see if you’re able to connect properly. For example, go to mail.google.com or mail.yahoo.com (or a different email provider) and use the same credentials that are triggering the “Configuration could not be verified” error. If you are successfully able to connect with the web client of your email provider using the same username and password, you’ve just confirmed that the credentials you’re using are correct. In case you manage to confirm that your credentials are correct, it’s very likely that the problem is occurring locally – In this case, move down to the next potential fix below.
Method 2: Installing the latest version of Thunderbird
You might also be encountering the “Configuration could not be verified” error due to Thunderbird bug that was occurring on Windows computers with versions 68.2.0 and older. According to the developer that fixed this problem, this problem might occur due to incorrect communications between Thunderbird and Mozilla Firefox (if it’s set as the default browser). Fortunately, this was resolved to start with version Thunderbird 68.2.1, so if you’re encountering this issue on a Windows computer and you’re using Mozilla as your default browser, just force the email client to update. To do this, open Thunderbird, click on the Help tab (from the ribbon at the top), then click on About Thunderbird (from the context menu) in order to force the application to update itself. If a new version is available, the app will update itself to the latest version available. Once the operation is complete, you will be prompted to restart – Do so by clicking on Restart Thunderbird to update. Once the application starts up again, attempt to connect with your email account and see if the error is fixed. In case you are still seeing the “Configuration could not be verified” error, move down to the next potential fix.
Method 3: Allowing Less Secure Apps (Yahoo and Gmail Only)
If you’re encountering this issue with a Yahoo or Gmail email address, it’s very likely that you’re seeing the “Configuration could not be verified” error due to the fact that your email client is not configured to allow less secured to sync data. Keep in mind that both Google and Yahoo are restricting less secured apps by default. But don’t go thinking that Thunderbird is not secure and you’re at risk of being hacked. Google and Yahoo will regard every 3rd party email client as ‘less secure apps’ – This includes Outlook, Thunderbird, Mailvird, SeaMonkey, etc. If this scenario is applicable to your current situation, and less secured apps are not allowed in your email provider settings, you can fix this problem simply by enabling this option. To do this, follow the guide that’s focused on the email provider that you’re using:
A. Allowing Less Secure Apps on Gmail
B. Allowing Less Secure Apps on Yahoo mail
In case you still end up seeing the “Configuration could not be verified” error, move down to the next potential fix below.
Method 4: Disabling Two-Step Verification
One of the biggest culprits that might end up causing the “Configuration could not be verified” error in Thunderbird is two-step verification. Keep in mind that it’s not just Thunderbird that will not work properly with two-step verification – Every major email client for the desktop will have problems with email accounts that are using two-step verification. Although there are certain workarounds there are not reliable, so the best course of action (if you are determined to connect your email client with Thunderbird) is to simply disable two-step verification. To help you do this, we’ve created 3 different sub-guides (one for each email provider with the most market share). Follow the guide that’s applicable to the email provider that you’re using:
A. Disabling Two-Step Verification on Outlook.com
B. Disabling Two-Step Verification on Yahoo
C. Disabling Two-Step Verification on Gmail
If you’ve already ensured that 2-step verification is disabled and you’re still encountering the “Configuration could not be verified” error, move down to the next potential fix below.
Method 5: Whitelisting Thunderbird in your Firewall settings
As it turns out, you can also expect to see the “Configuration could not be verified” error in a situation where your security firewall ends up blocking Thunderbird due to a false positive. Keep in mind that this is reported to occur with both Windows Firewall (the built-in suite) and with Avast and a few other 3rd party firewalls. If you’re using a firewall and you think this scenario is applicable, you might be able to fix the issue by adding the Thunderbird client to the list of whitelisted items. In case you’re using Windows firewall, follow the instructions below to whitelist the Thunderbird email client so that your firewall doesn’t block outgoing connections: Note: In case you are using a 3rd party firewall, search online for specific steps on how to whitelist applications. The steps will be different depending on the security tool that you’re using. In case you still end up seeing the “Configuration could not be verified” error, move down to the next method below.
Method 6: Enabling Cookies from Google on Mac (MacOS Only)
If you’re seeing this error message when trying to connect a Gmail account with the Thunderbird mail app on a Mac, it’s possible that the problem occurs due to the fact that Google cookies are not accepted. In this case, you should be able to fix the issue by accessing the Preferences menu of your Safari app and enabling 3rd party cookies. Several affected users have confirmed that this operation finally allowed them to get rid of the “Configuration could not be verified” error and use the Thunderbird app normally. Here’s a quick guide on enabling Cookies from Google on MacOS:
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