How to Fix the err_http2_protocol_error

The err_http2_protocol_error is a common issue that pops up in several types of systems and applications, which makes it rather difficult to pinpoint a routine list of solutions. It’s displayed in relation to a problem occurring within the HTTP/2 Network Protocol. HTTP/2 was developed as a replacement for the original Hypertext Transfer Protocol (HTTP) application layer and has since been standardized and adopted by most applications and systems as of 2015. Let’s go over what this application layer is, why we see the err_http2_protocol_error error within it, what are some commonly affected apps and systems, as well as some potential solutions for you. 

ERR_HTTP2_Protocol_Error as shown in Google Chrome

What does the err_http2_protocol_error mean?

The new HTTP/2 Network Protocol is an updated Hypertext Transfer Protocol version that most applications, systems, and internet browsers now run on. It helps applications run faster and simplifies how these systems communicate with one another. As a result, certain limitations of the original Hypertext Transfer Protocol, like being unable to support multiple requests at once or only allowing a single connection from a client, have been surpassed. 

HTTP 1.1 vs HTTP/2 protocol

The err_http2_protocol_error will pop up from time to time in applications where the HTTP/2 protocol isn’t yet supported or is outdated. Things like outdated network drivers, problematic responses from DNS servers, or something in tandem with these can cause communication errors between the HTTP application layer and the device you’re using. An example of this is if you’re using an older application in conjunction with Google Chrome, which supports the newer version of the HTTP protocol, or if you’re using a browser that doesn’t yet support the new HTTP/2, causing compatibility issues to pop up with certain websites or applications.  

What applications are affected by err_http2_protocol_error?

Unfortunately, this error is not limited to any specific type of application or system. However, it typically occurs in web browsers, such as Google Chrome and Mozilla Firefox, as well as in operating systems like Windows and macOS. Additionally, it can occur when trying to access certain websites or applications that use the updated protocol.

How to fix err_http2_protocol_error in internet browsers like Google Chrome and Mozilla Firefox

Due to the nature of this error, it’s less about correcting it and more about navigating around it and the updated HTTP/2 network protocol. However, there are several things you can do to see about resolving the err_http2_protocol_error.

1. Refresh the webpage.

When in doubt, refresh. The web browser equivalent of turning it off and on again doesn’t always work, but at times a website might just need a chance to try again to get it right.

2. Try using a different browser.

If one browser gets the error while another one doesn’t, there’s likely an error in the former. If both experience the error, it could be a communication error between the computer and the server you’re attempting to access. If this is the case, proceed to the next step.

Different internet browser options

3. Download and install any browser updates.

Believe it or not, errors like this do pop up on browser developers’ radar. Once they’ve found a fix for it, it’ll get released in an update for you to download and install. As such, you should see if there are any updates for your browser that you can do this with, as they may solve the problem for you.

4. Clear your browser data.

It’s possible that your browser cache may be harboring some corrupted files. Clearing these out may clear the error with them.

Here’s how to clear the cache in Google Chrome:

  1. Open your web browser and, in the address bar at the top, enter “chrome://settings/clearBrowserData”.
  2. Locate the Cache and Cookies options in the window that appears, select them, set the time range to All Time for them, then click on the Clear Data button at the bottom right.
Clear Browsing Data on Google Chrome can help in fixing the err_http2_protocol_error

5. Try resetting your browser entirely.

It’s possible there’s simply a bug somewhere that happens to be in the perfect spot to cause this error to occur. Resetting your browser will return it to factory settings, removing any bugs along with it.

Start by opening your browser, then click on the Settings option, usually in the top right-hand corner.

Under the advanced options, locate and click the option for reset, then select the button to reset all settings. When this is complete, restart the browser and test for the error again.

Reset Google Chrome to fix the err_http2_protocol_error

How to fix err_http2_protocol_error in other applications

As mentioned above, it’s not just web browsers that may experience this error, but anything trying to access a web server. While there are simply too many possible applications to go into detail, there are a few general things to look for and steps that you can take.

1. Try flushing your DNS.

Since this is typically a communication error between your application and a web server, it’s possible that flushing your DNS can resolve such an issue.

  1. Start by opening the Command Prompt. You can find it by pressing the Windows key and typing “cmd” into the search bar.
  2. In the Command Prompt window, type the following command, then hit the Enter key: “ipconfig /flushdns”
Flush DNS
  1. After a short delay, you should see a success message in the window. Type in “Exit” and hit Enter to close the window.
  2. Restart the computer and test the error again.

2. Check for server-side low disk space.

This solution method could be useful when you are the administrator of a server that’s returning the err_http2_protocol_error message. If your server is experiencing low or no disk space, responses sent from it can be cut off, leaving them no longer matching what their labels say they are. This causes applications to reject these responses and think they’ve lost access to the server altogether. If you can clear space or create more, it will likely resolve the error.

3. If using an NGINX server, disable GZIP.

Another potential solution for administrators. You can also try to disable gzip compression if you are using an NGINX server. To do this, you need to edit the NGINX configuration file. This can be done by opening up the text editor of your choice (such as vim, nano, or emacs) and editing the “nginx.conf” file. Once this file is open, you need to find the “gzip” line and comment it out by adding a “//” in front of it. 

You can also solve this error in the NGINX server block by setting GZip to off and then changing max temp file to zero, with the following code line: 

server {
gzip off; 
proxy_max_temp_file_size 0; 
location / { 

By doing this, you prevent the contents from being compressed twice. You can find more information about GZIP here. 

4. Check your antivirus software.

Another solution you can try is to check your antivirus software. Sometimes, these programs can mistakenly flag certain files or applications as malicious when they are not. This can cause problems with our systems and applications, so it’s important to check and see if this is the case. You can do this by opening up your antivirus software and checking the settings or the quarantine list to see if any of your programs are getting flagged. You can also try turning off your antivirus temporarily to see if that fixes the issue. 

5. If using 3.1 and React JS App, check your extensions.

There is an extension within React (which also applies to Visual Studio 2019) that can sometimes run into its own error and result in the err_http2_protocol_error issue. Removing this extension (Microsoft.AspNetCore.SpaServices.Extensions) and then updating to the latest version should resolve any problems.


The err_http2_protocol_error can be a frustrating problem to deal with. However, by trying some of the solutions that we have outlined in this article, you may be able to fix it and get back to using your applications and systems as normal.

If you are still seeing the error, try checking out the methods listed in our more generic guide on fixing the “this site can’t be reached” error message in Chrome.

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