4 Ways to Fix the ReferenceError: Browser is not Defined

Quickly solve the browser not defined console error

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Updated onJuly 2, 2024

updated onJuly 2, 2024

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ReferenceError: browser is not defined is a common issue in many popular browsers. It occurs when the browser isn’t properly referenced in the code for web design or testing.

Below, we’ll walk you through step-by-step instructions on how to fix this error for good.

How can I fix the browser not defined error?

1. Update your browser

If your browser is out of date, then issues may arise in the console. Regularly check for updates in your browser to avoid any future issues.

2. Disable add-ons

Users report that disabling add-ons like Ad-block has solved the problem. Disabling all of your extensions may fix the issue

3. Change the namespace

If you’re running into the ReferenceError:browser is not definedin Google Chrome, then you will need to change the namespace with callbacks frombrowser.*tochrome.*for cross-compatibility. You can do this by manually changing the namespace and callbacks tochrome.*which will work in both Chrome and Firefox.

Users can also use a shim or polyfill to convert thebrowser.*namespace tochrome.*with callbacks for Chrome. One shim to use is WebExtension which offers a lightweight polyfill library WebExtension APIs in Chrome.

4. Try another browser

If all else fails, consider using a different browser.

There are several causes of browser errors, but we noticed minimized issues in the Opera One browser. Switch to Opera One with all of your saved data from your existing browser and test the connection.

A browser’s undefined failure might be caused by an outdated version of the browser, but not in Opera. It is constantly updated and is known to be one of the most stable browsers out there.

Opera One

Why am I getting the browser not defined error?

The ReferenceError:browser not definedoccurs when there is a reference to a non-existent browser somewhere in the code when trying to create an extension. Declare the browser in reference or make sure it’s accessible in the script.

The browser variable declared within a function is not available outside of that function which could lead to the error. Defining the browser outside of the scope of function will make it accessible. Another possible cause could be a misspelling of the browser global variable.

Here are some variations of the error for browsers:

For other platforms:

We hope one of the above solutions helped you fix the browser is not defined. error. If you’re looking for recommendations for thebest browsers for developers, we have a guide for that. Let us know in the comments which solution worked for you or if you have a suggestion for a different solution.

4 Ways to Fix the ReferenceError: Browser is not Defined#

How can I fix the browser not defined error?#

1. Update your browser#

2. Disable add-ons#

3. Change the namespace#

4. Try another browser#

Opera One#

Why am I getting the browser not defined error?#