When WP Rocket breaks a page, a slider or a form, the cause can be a single setting, such as Delay JavaScript execution. You do not need to guess which checkbox to untick. Turn Delay JavaScript on with the other file optimisation options off and check the page. If the problem shows up, turn Delay JavaScript off and check again. If it goes away, you have found the cause.
WP Rocket’s own troubleshooting guide describes this test. It also says to fix any existing browser console errors first, because they can interfere with the test. Then decide whether the problem is cosmetic (an element shows up late) or functional (a form or slider does not work). For functional problems, exclude the affected script rather than switching the whole feature off.
Step 1: Confirm the setting is the cause
- In WP Rocket, turn on Delay JavaScript execution and turn off the other File Optimization options.
- Check the page. If the problem does not show up, Delay JavaScript execution is probably not the cause.
- If the problem does show up, turn Delay JavaScript execution off and check the page again. If the problem is gone, the feature is the cause.
Step 2: Decide what kind of problem it is
WP Rocket’s guide gives two priorities for cosmetic problems. You can exclude the affected scripts for the best visual experience, which costs speed. Or you can keep the scripts delayed for the best speed, and accept that visitors may have to wait or interact before some elements appear. For layout or functional problems, the guide says to exclude the affected files.
Step 3: Find the script to exclude
The guide suggests these ways to find it:
- Use the one-click exclusions, or add the script’s URL or a matching pattern to the Excluded JavaScript Files box.
- Inspect the broken element to find its class. Then open the page with
?nowprocketadded to the address, which bypasses WP Rocket’s optimisations, and use the browser’s developer tools Search tab to find the scripts that mention that class. - Use process of elimination, and narrow the exclusions down one script at a time.
Safe Mode is a last resort. It excludes most scripts, which removes much of the speed benefit.
If you are removing WP Rocket
Uninstalling from the WordPress admin, WP Rocket says it cleans up after itself: it removes its files and folders and its changes to .htaccess and wp-config.php. The uninstall page does not say whether cron events, database tables or options are removed too, so check those afterwards.
If you delete the plugin folder by hand, the guide lists these steps. Back up the whole site first, because they cannot be undone.
- Delete
wp-content/advanced-cache.php. - In
.htaccess, remove everything between#BEGIN WP ROCKETand#END WP ROCKET. - In
wp-config.php, setWP_CACHEto false or delete that line. - Delete the cache folders, starting with
wp-content/cache/andwp-content/wp-rocket-config/. - Remove WP Rocket’s cron events. WP Crontrol lets you search for “rocket” in its Cron Events tab.
- Remove WP Rocket’s database tables and its rows in the options table. The uninstall guide lists them, so check its list rather than deleting by name guesses.
Where ZeroConfig fits
If you would rather not choose these settings yourself, ZeroConfig has one switch and no settings to tune. Its Safety Check loads your home page, a post and a page with and without each feature. If a feature causes a new JavaScript error or changes the layout by more than 8 % of the screen, that one feature is switched off, the rest stay on, and the plugin tells you why. ZeroConfig is in beta, and it is free for one site.
Running two optimisers is slower than running one, and they fight over the same files. Deactivate WP Rocket before you turn ZeroConfig on. For a side-by-side look at the two, see ZeroConfig vs WP Rocket, and for how the Safety Check works, see the Safety Check section.
Sources
- WP Rocket, “Troubleshoot Delay JavaScript execution issues”, last updated 19 January 2026, checked 25 October 2026: docs.wp-rocket.me
- WP Rocket, “Uninstalling WP Rocket”, last updated 12 June 2026, checked 25 October 2026: docs.wp-rocket.me