Why does the Diff tab say "No previous scan to compare against."?

Why this happens

Diff needs two completed scans, because it works by comparing one with the other. It compares the scan you are viewing with the previous completed scan of the same target. A first scan has nothing before it, so the tab shows No previous scan to compare against. Nothing is broken.

A scan that failed or was cancelled does not count as a baseline. If your only earlier runs ended that way, the same message appears, even though the target has been scanned before.

How to fix it

1. Open Recent Scans. Look for earlier runs of this target. At least one must say Completed for a baseline to exist.
2. If you have fixes to test, deploy them first, so the next scan sees the new code.
3. Click Scan on the profile row, or on the row in Recent Scans, to run it again.
4. Wait until the new scan shows Completed. A small app takes roughly an hour, and you can leave the page while it runs because the work carries on without you.
5. Open the new scan and click Diff. The three columns now fill in.

Same profile both times is best. Then any change in the columns comes from your app, not from different settings.

Still not working?

Start with the simple checks, since most people who see this message on a second scan are looking at the wrong run or at a run that did not finish.

• Make sure you opened the newer scan. The older one will always say there is nothing before it, no matter how many runs follow.
• Check the result badge. A scan that failed still holds the findings it reached, but it cannot serve as a baseline.
• Read which scan the Diff tab compares against for the full rule.

Should a second completed scan still show the message, contact us. The compare scans tutorial has a worked example.

Related questions

• Which scan does the Diff tab compare against?
• How do I compare a scan with the previous one?
• How do I re-run a previous scan?
• What do Completed, Failed and Cancelled mean on a scan?
• How do I find findings that came back after being fixed?

Full tutorial

How to compare scans in Cyberlop with the Diff tab

Step-by-step, with annotated screenshots.

Updated 8 October 2026 · Back to the help centre