browser extension troubleshooting: support checklist

TL;DR

When a page breaks in a normal window but works in a private window, an extension did it. Find it with the disable-half method: disable half the extensions, test, and repeat on the failing half. It finds the culprit in logarithmic time. Then decide: allowlist the site, update or remove the extension, or report it. Do not let users run with everything disabled forever.

The query

browser extension troubleshooting: support checklist

Use this when

• Users report broken pages or features
• Slow browser complaints
• "Works in incognito" symptoms
• Writing browser troubleshooting guides

Not for

• Building browser extensions
• Extension security review
• Browser bugs (vendor's problem)
• Extension policy for managed devices

Steps

1. Confirm the extension hypothesis

Private/incognito window test. Works there, broken in normal: it is an extension (or cache; clear cache too to be sure). Broken in both: stop, it is not extensions.

Expected output: extension cause confirmed or ruled out.

2. Use the disable-half method

Disable half the extensions, test. Still broken: the culprit is in the enabled half. Fixed: it is in the disabled half. Repeat on the failing half. Ten extensions take four rounds, not ten.

Expected output: the culprit extension identified.

3. Identify the usual suspects first

Ad blockers, privacy tools, password managers, and coupon/shopping extensions cause most breakage. If the user has one, test it first before the full half-split. It is usually the ad blocker.

Expected output: quick win or proceed to full method.

4. Resolve: allowlist, update, or remove

Allowlist the site in the extension (best for ad blockers on trusted sites). Update the extension (old versions break on new page code). Remove it if it is abandoned or the breakage is severe. Tell the user which and why.

Expected output: the page works with a deliberate extension setup.

5. Document for the next ticket

Note the extension and the breakage in the ticket and the team notes. Extension conflicts recur across customers; the second ticket should start with the known answer.

Expected output: the conflict logged.

Template: the walkthrough

This looks like a browser extension interfering, [Name]. Let us find which one:

1. First, confirm: open a private/incognito window and try [the broken thing]. If it works there, an extension is the cause.
2. Go to your extensions page ([browser] menu, then Extensions).
3. Turn off half of them, then try the page again.
   - Still broken: the culprit is in the half still on. Turn off half of those.
   - Fixed: it is in the half you turned off. Turn half of those back on and test.
4. Repeat until one extension makes it break. That is the one.
5. For that extension: [allowlist our site / update it / remove it].

Start with your ad blocker if you have one; that is the most common cause. Tell me what you find.

Variant phrasings

page broken only in normal browser window

Steps 1 and 2. Confirm, then disable-half.

ad blocker breaking website

Steps 3 and 4. Test the ad blocker first, then allowlist.

which extension is causing problems

Step 2. The disable-half method, explained plainly.

Why it works

Extension conflicts are combinatorial: users cannot reason about ten interacting extensions, but binary search does not need them to. The private-window test is the perfect screen because it disables extensions by default. Logging the conflicts compounds the value across tickets.

Edge cases

• Managed devices: users cannot disable extensions. Route to their IT with the diagnosis.
• The extension is required (corporate security tooling): allowlisting the site is the fix, not removal.
• Multiple culprits: rare, but the half-split still works. Keep going after the first find if issues remain.
• Extension updates re-break: note the version. "It worked until Tuesday" usually means an auto-update.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_Kb5G1yW6p9uVg6oZhSHdeg