What to Do When You See the ERR_HTTP2_PROTOCOL_ERROR

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A comprehensive guide to solving the HTTP2 error

Co-authored by Darlene Antonelli, MA Reviewed by Luigi Oppido

Last Updated: October 3, 2024 Fact Checked

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Common Causes

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Common Fixes

Are you seeing a "ERR_HTTP2_PROTOCOL_ERROR" message in your browser? This error can appear no matter what browser or operating system you're using since it's an error message you can encounter on any website. Most updated or modern websites use the HTTP/2 network protocol, so issues with the network, your browser, or third-party software can trigger the error message.

ERR_HTTP2_PROTOCOL_ERROR Causes

You'll see this error when a web server and a browser cannot communicate or are constantly interrupted. Causes include incompatible and outdated software, corrupted cache, and firewall configuration. As a website host, check your SSL and server configuration.

Section 1 of 2:

What Causes ERR_HTTP2_PROTOCOL_ERROR?

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If your browser or computer is outdated, they can be incompatible with some websites.
Corrupted cache files can prevent sites from successfully validating your device, resulting in the "ERR_HTTP2_PROTOCOL_ERROR" message.

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Some third-party extensions can interrupt communication between your computer and the website's server, which prevents the website from loading properly or triggering the error message.
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Third-party antivirus or firewall software. Some third-party firewalls can prevent you from accessing certain sites due to security settings.
- If you're hosting a site and running into this issue, there are other things you need to watch out for, including:
  - Incorrect SSL configuration
  - Incorrect HTTP/2 settings with the website's server
  - No disk space on server

Section 2 of 2:

Common Fixes

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1
Update your browser. Since outdated software can house many bugs and glitches, it's best to keep everything updated.
- Most browsers, like Chrome, Safari, Edge, and Firefox, update automatically whenever you open a new window.
- You can generally find an option to update your browser in the "Settings" menu (sometimes the "About" page), although the specific steps are slightly different for all web browsers. Read |this wikiHow article for more specific updating instructions for your browser.
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Clear browser data. Since corrupted data and cached files can trigger the error message, you want to delete what your browser has stored to see if the page will load.
- Chrome: Press Ctrl + Shift + Del, select the data to delete, and pick a time range. Click Delete data when done.
- Safari: Go to Safari > Settings > Privacy > Manage Website Data and select all sites to clear website data. Finally, click Remove or Remove all.^{[1]
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- Edge: Go to ••• > Settings > Privacy, search, and services > Choose what to clear then pick a time range and select all the boxes to clear everything from your browser. Click Clear now when you're done.^{[2]
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- Firefox: Click ☰ > Settings > Privacy & Security > Clear data. Choose the data to delete and click Clear.^{[3]
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- You can read this wikiHow article for specific steps to clear your browser data according to what browser you're using.
- Alternatively, use a Private or Incognito window so you don't have to delete your browsing history. Since this doesn't solve the error in your main browser, it's a temporary solution that'll let you access the site quickly.
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Disable browser extensions. Since some extensions can interrupt communication between your computer and the website's server, turning these off will eliminate that interruption so the page can load.
- Generally, you can find a "Manage extensions/Add-ons" page in the Settings menu, or inside the three dot/line menus.
- Follow the steps outlined in this wikiHow article to disable your extensions or add-ons for your specific browser.
- You can turn them on one by one and load the page to see if you get the error message; as soon as you do, you know that the last extension/add-on you turned on is causing the error message. Then, you can update or uninstall that extension/add-on.
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Check your firewall or antivirus settings. Follow the steps in this wikiHow article to check your Firewall and see if it's blocking the site.^{[4]
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- If you're confident that the site you're trying to see isn't malicious, you can turn off your firewall or antivirus software on your computer. You can also open ports to allow the traffic from that site.
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Hosting a site solutions:
- Check that the SSL certificate is configured correctly and has not expired.
- Make sure the web server isn't out of space and that it has HTTP/2 configured correctly.
- Update your server software.
- Contact your hosting provider to check for issues.