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Fix JavaScript that will not run

We'll confirm JavaScript is enabled, check the console for errors, and rule out extensions—so you know why scripts fail and how to fix it.

Troubleshooting · Home maintenance
5–15 min
What you'll need
  • Browser (Chrome, Firefox, Edge, or Safari)
  • Access to browser settings and DevTools (F12)
Step 1 of 7

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Steps

Goal: Enable JavaScript, check the console for errors, and rule out extensions so scripts run.

  • Check if JavaScript is enabled in your browser settings.
  • Good: It was disabled—enable it and reload. The site should work.
  • Bad: Already enabled—proceed to Check the console.

Check if JavaScript is enabled

Goal: Ensure the browser allows JavaScript.

  • Chrome: Settings → Privacy and security → Site settings → JavaScript → “Sites can use JavaScript” on.
  • Firefox: about:config → search javascript.enabled → set to true.
  • Edge: Settings → Cookies and site permissions → JavaScript → Allowed.
  • Safari: Preferences → Security → Enable JavaScript.
  • Good: JavaScript was disabled—enable and reload. Bad: Already enabled—check the console.

Check the console for errors

Goal: See why scripts fail.

  • Press F12 to open DevTools. Click the Console tab.
  • Reload the page and reproduce the problem. Red errors show the cause.
  • net::ERR_BLOCKED_BY_CLIENT—often an extension blocking the request. Disable extensions.
  • Refused to execute or CSP—Content Security Policy blocks the script. Site owner must fix.
  • Mixed Content—script loads over HTTP on an HTTPS page. Scripts must use HTTPS.
  • Good: You see the error. Fix based on type. Bad: No errors—proceed to Try incognito.

Try incognito

Goal: Rule out extensions.

  • Open incognito (Chrome/Edge: Ctrl+Shift+N; Firefox: Ctrl+Shift+P). Load the site.
  • Good: Site works in incognito—an extension blocks scripts. Proceed to Disable extensions.
  • Bad: Still fails—try another browser or clear cache.

Disable extensions

Goal: Find which extension blocks JavaScript.

  • Chrome: chrome://extensions. Firefox: about:addons. Edge: edge://extensions.
  • Disable half of your extensions, reload, test. Narrow down to the culprit.
  • Script blockers (NoScript), ad blockers, and privacy extensions often block scripts. Whitelist the site or disable the extension for it.
  • Good: You found the extension. Whitelist or disable for the site.
  • Bad: All disabled and still fails—clear cache or try another browser.

When to get help

  • JavaScript is enabled, no extension blocks it, and the console shows no fixable errors—the problem may be the site. Contact site support with the console error.
  • The site works for others but not you—update your browser and try again.

Verification

  • Buttons, forms, and dynamic content work on the site.
  • No red errors in the console (or only errors you cannot fix).
  • If an extension was the cause, it is whitelisted or disabled for the site.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Enable JavaScript Check browser settings—JavaScript may be disabled.
  2. Check console F12 > Console—red errors explain the failure.
  3. Try incognito Rule out extensions.
  4. Disable extensions Find which extension blocks scripts.
  5. Get help Site issue or unsupported browser—contact support.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Browser and version
  • Site URL
  • Console error messages (copy full text)
  • Extensions installed
  • Steps already tried

Is JavaScript enabled in the browser?

Browsers can disable JavaScript in settings.

Chrome: Settings → Site settings → JavaScript. Firefox: about:config → javascript.enabled. Edge: Settings → JavaScript. Safari: Preferences → Security. Ensure JavaScript is allowed. Good: it was disabled—enable and reload. Bad: already enabled—check the console.

Yes No

You can change your answer later.

Enable JavaScript and reload

Enable JavaScript in browser settings. Reload the site. The scripts should run.

Done

Does the console show errors?

F12 > Console. Red errors explain why scripts fail.

Press F12, open Console. Reload and reproduce. net::ERR_BLOCKED_BY_CLIENT: extension blocking—disable extensions. CORS or CSP: site configuration. Mixed Content: script loads over HTTP on HTTPS page. Good: you see the cause. Bad: no errors—try incognito.

Yes No

You can change your answer later.

Fix based on error type

ERR_BLOCKED_BY_CLIENT = extension. CORS/CSP = site. Mixed Content = HTTPS/HTTP.

Extension: disable extensions, whitelist site. CORS/CSP: site owner must fix. Mixed Content: ensure scripts load over HTTPS. Good: you fix it. Bad: site issue—contact support.

Done

Does the site work in incognito?

Incognito disables extensions.

Open incognito (Ctrl+Shift+N or Cmd+Shift+N). Load the site. Good: works in incognito—extension blocks scripts. Disable extensions one by one. Bad: still fails—try another browser or clear cache.

Yes No

You can change your answer later.

Disable extensions one by one

Chrome: chrome://extensions. Firefox: about:addons. Disable half, reload. Find the extension that blocks scripts. Whitelist the site or disable for it.

Done

Try another browser or clear cache

Open in different browser. If it works, the failing browser has a setting or extension. Clear cache for the site and retest. If still fails, contact site support.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would JavaScript not run on a site?
JavaScript can be disabled in browser settings, blocked by an extension (ad blocker, privacy tool, NoScript), or failing due to errors. Check the console (F12) for red error messages.
How do I enable JavaScript in my browser?
Chrome: Settings → Privacy and security → Site settings → JavaScript → Allowed. Firefox: about:config → javascript.enabled = true. Edge: Settings → Cookies and site permissions → JavaScript → Allowed. Safari: Preferences → Security → Enable JavaScript.
What do console errors mean?
Red errors in DevTools > Console show why a script failed—e.g. "blocked by CORS," "net::ERR_BLOCKED_BY_CLIENT" (extension), or "Uncaught TypeError." The message often points to the fix.

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