Previews

Symptom

The client cannot open a preview, or Settings → Previews is yellow. Home may say the project name, then "preview check failed".

Waiting for the first preview does not by itself turn the mark yellow. The line "Waiting for the first request to confirm." is only the detection note. See Health indicators.

Causes

No preview has been detected yet

Confirm. Previews says "No preview has been detected yet." There is no "Last preview" link. The mark stays green when a host is already known. After several requests with no preview URL, the status becomes "No preview URL arrived after several requests." The inbox status for that request is No preview.

Fix. Ship one request far enough for the host to emit a preview deployment. If previews are turned off, the status is Off and the text is "Previews are turned off for this project." Turn on Show previews to clients. See Protected previews.

The preview is protected and there is no bypass

Confirm. The mark is yellow: "Previews are protected. Connect Vercel or add a bypass secret so clients can open them." The preview status is Blocked: "Previews are protected. Your client will hit a login screen." Vercel Deployment Protection is on, and Modifee has no bypass secret.

Fix. Connect Vercel so Modifee can create the bypass secret labeled "Modifee client previews", or paste the protection bypass secret and redeploy. MDF-VERCEL-002. MDF-VERCEL-003 when the preview URL is missing, protected, or not deployed. See Protected previews.

The last preview check failed

Confirm. The mark says "The last preview check failed. Run it again from the project." Home is red: the project name, then "preview check failed".

Fix. Open the project and run the preview check again after the deployment is ready. If the check keeps failing, treat it as a protected preview or a bad host and use the causes above. MDF-VERCEL-003.

No preview host was detected

Confirm. The mark says "No preview host detected. Add where this site is hosted." The detection line is "No preview detected yet". It is not the same as "Waiting for the first request to confirm.", which means a host is known and no preview has arrived.

Fix. Connect the host Modifee can recognize, or set where the site is hosted, then run another request. A known host with zero previews stays green. An unknown host does not.