Troubleshooting

Add to Chrome or Add to Firefox is unavailable

A disabled Add to Chrome or Add to Firefox button means that browser's official listing is not available yet. Chrome and Firefox availability are separate. Public installation is only through the Chrome Web Store or Firefox Add-ons on addons.mozilla.org; there is no source-install fallback. Check Getting started for current availability.

Chrome 120+ is the baseline. Edge, Brave, Opera, and Vivaldi also support Chrome Web Store extensions, but that does not mean every SnapDiff feature has been validated in each browser. Firefox 153+ is a new limited-feature desktop target, not a claim of a published listing or complete browser validation. See Browser compatibility. Mobile browser installs are not supported. If the store blocks installation on a managed browser, ask your browser administrator.

Device or language options are disabled in Firefox

This is intentional. Responsive device presets and browser locale simulation are not available in Firefox, including Pro. Use normal viewport, area, or full-page capture instead. Existing responsive/localized captures remain reviewable and exportable, but Firefox cannot create new such simulated captures. Libraries do not automatically synchronize between browsers.

SnapDiff asks to reload

After an extension update, the popup and background service may need to reconnect. Save editor changes, wait for active capture to finish, and choose Reload SnapDiff in the popup. Then reopen it.

Reloading the same installation keeps captures, drafts, settings, and the license. Do not uninstall or clear storage as a first fix. See updates and reload notices.

Capture fails or the page changes

• Use Chrome 120+ or Firefox 153+. Regular web pages support the most tools; protected stores and non-HTTP pages use screenshot-only capture where the browser permits it.
• Keep the source tab visible and unchanged until its capture finishes.
• On Chromium, close DevTools and leave the debugger notice open. Firefox does not use Chrome's debugger.
• Wait for the page to settle, especially if images, animations, or infinite scrolling keep changing the layout.
• For Area, stay on the same scroll position and drag the selection again. Scrolling, resizing, page changes, or the 90-second selection timeout cancel it.
• On Chromium, language capture automatically follows same-origin redirects during its reload and waits for the page to settle. Redirects to another scheme, hostname, or port are blocked; open that destination first and capture there.

A failed attempt does not consume another workflow. Start with Single → Viewport → Current tab → Browser default to narrow down a capture problem.

For language captures on live feeds such as LinkedIn, SnapDiff automatically waits for the refreshed page's same-origin data requests and visible content to settle. The reload may change the posts shown. If navigation, data requests, or content never settle within 30 seconds, SnapDiff stops without charging a completed workflow rather than capturing an unstable page.

Chrome says the extensions gallery cannot be scripted

The Chrome Web Store is a protected page. Chrome blocks the debugger and scripts needed for device presets, full-page and area capture, language simulation, and accessibility checks there. Closing DevTools or upgrading to Pro does not remove this restriction.

SnapDiff disables Capture for these combinations and provides Use screenshot-only to switch this popup to a plain visible-page screenshot without changing saved capture preferences. Alternatively, choose Viewport, Current tab, Browser default, and turn Check accessibility off. This uses the browser's visible-tab capture capability; browser policy can still restrict it. To use device presets or the other tools, open a regular website instead of its Chrome Web Store listing.

A full-page capture is too large or incomplete

On infinite feeds, SnapDiff captures the height loaded at the start and ignores posts appended below that boundary while scrolling. A virtualized feed that removes or repositions content inside the capture region can still fail; use a viewport capture rather than saving a broken stitch.

SnapDiff rejects pages that exceed its limits instead of saving a partial capture. A full-page capture supports up to 128 million native pixels, 100,000 pixels tall, and 16,384 pixels wide, whichever limit is reached first. An individual viewport must fit within the 16-million-pixel screenshot limit.

Browser zoom and display scaling affect native pixel dimensions. Try a shorter page, a smaller browser window, or a focused Area capture. Responsive presets are another option on Chromium only. Pages that shrink, change layout within the captured region, or prevent scrolling may not capture reliably. Secondary scrolling panels are not expanded, and the main scrolling panel must fit in the browser viewport.

Local files and browser-internal pages

Use screenshot-only capture for file:, about:, chrome:, and other non-HTTP pages. This does not enable page scripting or bypass browser restrictions. Some pages remain uncapturable, depending on the browser and its policies.

In Chrome, local-file screenshots require Allow access to file URLs in SnapDiff's extension details. Enable that setting yourself, then reopen the popup on the file. SnapDiff does not change the permission automatically.

Pixel Diff is unavailable or misleading

Multi always uses visual review, not pixel Diff. A/B pairs with different device viewport sizes also use side-by-side review without a Diff score.

For pixel comparison, capture A and B with the same viewport, zoom, and page state. SnapDiff aligns native pixels at the top-left and does not resize originals. Dynamic content, font loading, and layout differences can all create real pixel changes that are not necessarily defects.

The chosen language did not change the page

Language simulation is Chromium-only and is disabled in Firefox. It is not translation. The page must support the locale, and its URL, cookies, settings, or language picker may override browser preferences. Open the site's intended localized page and try again.

Save unsaved edits before Reload & capture. See the reload and shared-renderer limitations.

An export is too large

Switch to PNG when JPEG or WebP limits are exceeded. JPEG and WebP support up to 32 million pixels, with maximum sides of 16,384 and 16,383 pixels respectively. The format picker indicates when PNG is required.

A combined A/B or Multi export can be much wider than an individual capture. Use shorter pages or a smaller group if needed. Very large PNGs can also exceed the memory available in an external image viewer. SnapDiff will not silently resize originals to fit.

If a save dialog appears, check your browser's download settings. In Chrome, check Ask where to save each file before downloading at chrome://settings/downloads; in Firefox, check Always ask you where to save files under Files and Applications. Browser policy or security warnings may still require confirmation.

An accessibility report failed or has no findings

Not checked means that accessibility checking was not enabled for that capture; a saved screenshot cannot be scanned retroactively. Scan failed is not a pass. Capture again with Check accessibility enabled, DevTools closed, and the source tab visible.

Checks are bounded to 30,000 DOM elements and approximately 20 seconds. Embedded frames and closed shadow roots are outside coverage. Reports disclose omitted or shortened details. No findings does not establish accessibility compliance; review the scan scope and manual checks.

Captures are missing or storage is full

Check that you are in the same browser profile and extension installation. Libraries do not synchronize across installations or between Chrome and Firefox. Uninstalling, clearing extension storage, or removing the profile can delete local data.

If storage is full, download important images and reports before deleting captures you no longer need. Do not clear all extension storage as a first fix. There is no cloud restore; see privacy and protecting your work.

Pro will not activate

Use the license key supplied with your active SnapDiff Pro subscription.

For a legitimately issued key, paste it carefully into the extension's license dialog, check connectivity, and verify that the key matches the configured product and environment. An active Pro subscription supports up to 3 browser installations; deactivate an unused installation before moving it.

Previously verified access may continue temporarily offline, with weekly license rechecks. Deactivation is not subscription cancellation. See Free and Pro for purchase, renewal, and cancellation details.