What is ERR_HTTP2_PROTOCOL_ERROR​​ and how to fix it?

The ERR_HTTP2_PROTOCOL_ERROR error is one of the common problems that users may encounter when accessing websites. This error occurs when there is a problem in the communication between the browser and the web server via the HTTP/2 protocol, the latest version of the HTTP protocol, designed to improve data transfer efficiency. 

So what is the cause of this error and how to fix it? Find out with  TipsMake  in the article below. 

What is Err_http2_pro tocol_error?

Err_http2_pro tocol_error occurs when the web browser is misconfigured or fails to create a secure connection between the client and the server via the SSL/TLS protocol. When this error occurs, the message "This site can't provide a secure connection" will appear on the screen. Err_http2_pro tocol_error occurs, meaning that the website will not be accessible.

In addition to the message "This site can't provide a secure connection", some browsers will have different messages such as:

On Google Chrome: "This site can't provide a secure connection" or "Your connection is not private"

● Firefox: "Your connection is not secure".

● Safari: "Safari can't verify the identity of the website".

● Microsoft Edge: "There is a problem with your website's security certificate"

What causes the Err_http2_protocol_error error?

The Err_http2_pro tocol_error error can occur due to one of the following reasons:

● Incompatible, outdated software: If you use very old browser versions, you will not be able to access some websites because the browser is not compatible.

● Corrupt cache data: Corrupt cache files will prevent websites from successfully identifying the device.

● Extensions: Extensions interrupt the communication between your computer and the website's server so you can't load the web properly.

● Antivirus or firewall software: Some websites have security settings that third-party software may block your access to.

Err_http2_protocol_error troubleshooting measures

For browser errors

When you encounter the err_http2_protocol_error error, you can start troubleshooting it with simple steps. First, try refreshing the web page using the F5 key. If the website is temporarily down, this may resolve the error.

Also, try accessing the site using a different browser or closing some open tabs. If the error persists, continue with the other troubleshooting methods.

1. Update your browser

If you are using an outdated browser, this may cause HTTP/2 protocol errors due to incompatibility. To fix this, update your browser.

For Google Chrome, click the three-dot icon in the upper-right corner and select "Update Google Chrome." If you don't see the update button, go to "Help" > "About Google Chrome" to check for updates.

If you use Google Chrome on mobile, open the App Store or Play Store to check for and install updates.

2. Clear browser data

When you're having rendering issues, you should clear your browser data, including cache, cookies, and history, to help authenticate your device to websites. Here's how to clear search data in some popular browsers:

● For Google Chrome, go to More Tools > Clear Browsing Data and choose to clear Cached images and files, as well as history and cookies.

● For Safari, select Safari > Clear History and choose the time period to clear cache, cookies, and data.

● In Mozilla Firefox, click the hamburger icon, select History and then Clear recent history, making sure to check Cache.

After clearing your data, try accessing the website again. If you still get the err_http2_protocol_error error, you will need to look for other solutions.

3. Open a private or incognito browser window

When you visit a new website, your browser caches information to speed up loading when you return. You can avoid clearing your cache when you encounter an HTTP/2 protocol error by opening your browser in private or incognito mode.

In Google Chrome, go to the menu and select New incognito window. From there, try accessing the site again. This is a temporary solution that saves you from having to clear your cache or disable extensions.

4. Disable or uninstall Browser Extensions

Third-party extensions can affect the way your browser interacts with the website, leading to the err_http2_protocol_error error. You should try disabling these extensions to test.

In Google Chrome, go to More tools > Extensions. Here, disable each extension using the switches in the lower right corner. Once disabled, try accessing the error site again.

If the page loads successfully, go back to the Extensions page and enable each extension one by one, checking to see if the error reappears. Once you find the extension causing the problem, consider removing it completely.

5. Disable QUIC protocol

QUIC (Quick UDP Internet Connections) is a cryptographic network protocol developed by Google to speed up and secure HTTP traffic. Only 8% of websites currently use QUIC, so sites that are not configured for this type of traffic may cause HTTP/2 errors.

To solve the problem, you can disable the QUIC protocol in your browser.

In Chrome, type in the address bar: chrome://flags/#enable-quic Find the Experimental QUIC protocol entry and set it to Disabled. Then, restart your browser to apply the change and check for incompatible websites.

6. Restore browser default settings

When using Google Chrome, minor glitches can change the default settings, resulting in errors like err_http2_protocol_error. To restore the browser to its default settings, do the following:

● Open Settings.

● Go to the Reset settings tab on the left and select Restore settings to factory defaults.

● Confirm to delete current settings. Note that this will delete your search history, startup page, extensions, and bookmarks, returning the browser to its original state.

Additionally, you can reset the experimental settings by going to: chrome://flags/

Here, select Reset All to restore experimental features to default settings.

For device errors

1. Reset the device's date and time

It is important to display the correct date and time on the device, as incorrect information can lead to err_http2_protocol_error errors.

● On Windows, right-click the clock in the lower-right corner and select Adjust date and time. If the time isn't automatically correct, turn off Set time automatically and make sure the time zone is correct. Then, click Change to set the date and time manually.

● On Mac, click the Apple menu and select System Preferences. Find Date & Time, click the lock to change it, uncheck Set date and time automatically, and enter the correct value. Once adjusted, try accessing the website again!

2. Update the operating system

If your device hasn't been updated in a while, this can cause performance issues and conflicts with websites. To fix this, check for and install recent updates.

● On macOS: Make a backup, then go to System Preferences > Software Update. You'll see available updates; click Update Now to install.

● On Windows: Go to Start > Settings > Windows Update and install the latest update.

After updating, check to see if the HTTP/2 error is resolved. If the problem persists, try other methods.

3. Clear DNS

The Domain Name System (DNS) acts as an index for websites and their IP addresses. When you visit a website, this information is stored in a database, which speeds up the loading of pages that are visited again.

If you encounter the err_http2_protocol_error error, you can clear the DNS cache to remove the IP address and other DNS data from your computer.

● On macOS: Open Terminal and enter the command: sudo killall -HUP mDNSResponder

● On Windows: Open Command Prompt and paste the command: ipconfig /flushdns

You will receive a confirmation message once the DNS cache has been cleared!

4. Check your antivirus software

To protect your computer while browsing the web, you may have installed anti-virus software. While they provide many benefits, they can sometimes misbehave and flag legitimate applications as malicious, blocking access to certain websites.

If the previous measures did not work, check your antivirus software. Open notifications to see new security issues and check the quarantine list to see if any unwanted applications have been flagged. If so, you may need to temporarily disable your antivirus software.

Conclude

To fix the ERR_HTTP2_PROTOCOL_ERROR error, users can take some simple steps such as updating the browser, clearing the cache, or checking the server configuration. If these measures do not work, users may need to consider adjusting security settings or even contacting the hosting provider for support.

Samuel Daniel

Update 12 February 2025