diff --git a/web/public/locales/en/views/settings.json b/web/public/locales/en/views/settings.json
index a1e14452e..012023b37 100644
--- a/web/public/locales/en/views/settings.json
+++ b/web/public/locales/en/views/settings.json
@@ -415,6 +415,7 @@
         "audioCodecGood": "Audio codec is {{codec}}.",
         "resolutionHigh": "A resolution of {{resolution}} may cause increased resource usage.",
         "resolutionLow": "A resolution of {{resolution}} may be too low for reliable detection of small objects.",
+        "resolutionUnknown": "The resolution of this stream could not be probed. This will cause issues on startup. You should manually set the detect resolution in Settings or your config.",
         "noAudioWarning": "No audio detected for this stream, recordings will not have audio.",
         "audioCodecRecordError": "The AAC audio codec is required to support audio in recordings.",
         "audioCodecRequired": "An audio stream is required to support audio detection.",
diff --git a/web/src/components/settings/wizard/Step4Validation.tsx b/web/src/components/settings/wizard/Step4Validation.tsx
index 8352a1c75..b739fe1ab 100644
--- a/web/src/components/settings/wizard/Step4Validation.tsx
+++ b/web/src/components/settings/wizard/Step4Validation.tsx
@@ -607,23 +607,38 @@ function StreamIssues({
       }
     }
 
-    if (stream.roles.includes("detect") && stream.resolution) {
-      const [width, height] = stream.resolution.split("x").map(Number);
-      if (!isNaN(width) && !isNaN(height) && width > 0 && height > 0) {
-        const minDimension = Math.min(width, height);
-        const maxDimension = Math.max(width, height);
+    if (stream.roles.includes("detect") && stream.testResult) {
+      const probedResolution = stream.testResult.resolution;
+      let probedWidth = 0;
+      let probedHeight = 0;
+      if (probedResolution) {
+        const [w, h] = probedResolution.split("x").map(Number);
+        if (!isNaN(w) && !isNaN(h)) {
+          probedWidth = w;
+          probedHeight = h;
+        }
+      }
+
+      if (probedWidth <= 0 || probedHeight <= 0) {
+        result.push({
+          type: "error",
+          message: t("cameraWizard.step4.issues.resolutionUnknown"),
+        });
+      } else {
+        const minDimension = Math.min(probedWidth, probedHeight);
+        const maxDimension = Math.max(probedWidth, probedHeight);
         if (minDimension > 1080) {
           result.push({
             type: "warning",
             message: t("cameraWizard.step4.issues.resolutionHigh", {
-              resolution: stream.resolution,
+              resolution: probedResolution,
             }),
           });
         } else if (maxDimension < 640) {
           result.push({
             type: "error",
             message: t("cameraWizard.step4.issues.resolutionLow", {
-              resolution: stream.resolution,
+              resolution: probedResolution,
             }),
           });
         }