The scan does not start
Scans run in the background through a request from your site to itself, called a loopback request. If something blocks that request, the progress bar disappears after about 20 seconds and the plugin shows a warning.
Common causes are a maintenance or coming soon mode, a plugin that requires a login for the whole site, or a host that does not allow loopback requests. Tools → Site Health tells you whether loopback requests work on your site. If it reports a problem there, your host can usually fix it.
“The API key appears to be invalid”
- Copy the key again from the Credentials page in Google Cloud Console. A missing character is enough to break it.
- Make sure the PageSpeed Insights API is enabled in the same project as the key.
- Check the key’s restrictions. A Websites restriction blocks the plugin, see Get a Google API key.
Use Check key in the settings. It tells you which of these is the problem.
“The daily API quota is used up”
Google allows 25,000 requests per project per day. The plugin stops the scan when the limit is reached instead of failing on every remaining page. Start the scan again after midnight Pacific Time and it picks up the pages that were not checked yet. If several sites share one key, give each site its own project and key.
“The last scan did not finish”
Your host stopped the scan before it was done. Go to Settings → Advanced and raise Maximum execution time. If that does not help, set Maximum script run time to 30 seconds so the scan restarts itself in smaller pieces.
A page was added to Ignored URLs
Google could not load it. See Ignored URLs for the usual reasons and how to bring it back.
My scores are different from pagespeed.web.dev
Lab scores change a little with every run, mostly because of how fast your server answers at that moment. Recheck the page and the numbers usually come closer. Compare the same report type too: desktop and mobile scores are always different.
There is no real-user data
Google only publishes Chrome UX Report data for pages and sites with enough visitors. Smaller sites often have none. The lab results still show what to improve.
Reports only show a Performance score
Reports made before version 5.0 only stored the Performance score. Tick Recheck all and click Start scan to fill in Accessibility, Best Practices, SEO, AI Agents and the Core Web Vitals.
A screen shows “This screen could not be displayed”
Click Reload page. Right after an update, your browser sometimes still has old files cached. If the message comes back, open Technical details and include that text when you ask for help.
Still stuck?
Ask on the WordPress.org support forum. Mention your WordPress version, your host, and what you see on the Logs screen if API errors are logged.