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Troubleshooting & FAQ

What to do when TruePx can’t start on a page, a check can’t finish, or a result looks wrong, and answers to common questions.

TruePx won’t start on a page#

A red ! on the toolbar icon means it couldn’t start there; hover the icon to read the reason.

• Chrome’s own pages (chrome://…, the new-tab page, settings), the Chrome Web Store and other extensions’ pages: Chrome doesn’t let any extension run on them. Nothing to fix.
• Files on your computer (file://…): open chrome://extensions, click Details under TruePx and turn on Allow access to file URLs.
• A normal website: reload the tab and turn TruePx on again. If it still fails, the reason under the icon says what went wrong; please send it to us.

Links and buttons don’t work while TruePx is on#

That’s on purpose: clicks select elements so you can measure them. Press P to pause inspection and use the page, or turn TruePx off. After you turn it off, everything works as normal.

The side panel is empty#

• “Select an element on the page”: click an element; the Element tab shows the one you select.
• “Activate the ruler on the page to collect page data”: TruePx is off in this tab. Turn it on, then open the panel from the dock (0).
• The Page tab shows old data: click Refresh.

“Screenshot blocked”#

Chrome stopped allowing TruePx to capture this tab, usually because the tab went to another site after you turned TruePx on. Turn TruePx off and on with the toolbar icon, then try again. Granting all-sites access avoids it.

A contrast result says it couldn’t be measured#

Each row says why. The common reasons, and what to do:

• Text on a photo, gradient, video or under another layer: there’s no single background color. TruePx measures the pixels behind the text when it can; otherwise check it by eye or with the color picker.
• “what’s painted behind it keeps changing” or “it kept moving”: a video, slideshow or animation is behind it, so one screenshot can’t judge it. Check it by eye at its lightest and darkest moment.
• “a banner or pop-up fixed on the screen covers it”: close the cookie banner or pop-up and run the check again.
• “it’s beside the screen”: it’s a carousel slide that isn’t showing. Show that slide and check again.
• “the page wasn’t the visible tab”: you switched tabs or windows while the check ran. Stay on the tab until it finishes.
• “TruePx isn’t allowed to take a screenshot of this tab now”: click the TruePx icon on the tab again, or grant all-sites access.

Text that only appears when you scroll is measured best with Check the whole page.

The SEO or Audit tab says “This is … bot check, not the site’s page”#

A service such as Cloudflare showed a challenge (“Verify you are human”) instead of the page, so there was nothing of the site to check. Complete the challenge, wait for the real page, then click Refresh or Re-run.

Check links or the language-version check asks for permission#

Requesting other sites’ addresses needs Chrome’s permission. Click the button again and choose Allow, or grant all-sites access once. Links that answer 401, 403 or 429 are sites that refuse automated checks; open them yourself to confirm.

Google’s test doesn’t run#

• “Google can only test pages that are public on the internet”: local, staging or logged-in pages can’t be tested by Google. Use the Performance numbers TruePx measures in your browser.
• “Google’s free shared limit is used up for today”: paste your own free API key (the link shows how to get one) and click Save and test.

The grammar check stops#

• “LanguageTool’s free limit was reached”: wait a minute and try again.
• “There are no full sentences on this page to check”: it checks sentences only, not menus, buttons or single words.

Measure the real page load fails#

“Couldn’t measure the page load”: let the page finish loading, then try again. If it asks for access to the site, allow it; it watches only this tab’s reload.

A responsive viewport stays empty#

The site refuses to be shown inside another page. Grant all-sites access so the preview can lift that for this tab, then click Refresh. See pages that block framing.

The page looks wrong after editing#

Use Undo on the dock (⌘/Ctrl Z), or Revert All in the Changes tab. Reloading the page also brings it back, except for saved CSS rule edits, which come back when you turn TruePx on there; revert them in the Changes tab.

A keyboard shortcut does something else#

Another extension or app may use Alt Shift S. Change TruePx’s shortcuts at chrome://extensions/shortcuts. The number keys and P only work while TruePx is on and you’re not typing in a field.

Questions#

Is TruePx free?#

Yes, everything, with no account.

Do my edits change the real website?#

No. Edits only change the page in your own tab. Copy the CSS from the Changes tab into your code to make them real.

Does TruePx collect my data?#

No. It has no analytics or tracking and sends nothing to its developer. See what TruePx sends and the privacy policy.

Which browsers does it work in?#

Desktop Chrome 116 or newer, installed from the Chrome Web Store.

How is the Audit different from Lighthouse?#

Lighthouse loads the page in a lab. The Audit checks the page as it is in your tab, including what you scrolled to and clicked, logged in or not, and adds checks Lighthouse doesn’t have (secrets in scripts, tracking before consent, placeholder text, typos, design consistency). For Google’s lab score, run Google’s test from the Audit tab.

Found a bug or have an idea?#

Email hello@truepx.xyz with the page address and what you saw. A screenshot helps.