diff --git a/CHANGELOG.md b/CHANGELOG.md
index 454f0230..0f2fb050 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,10 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Added
+
+- 🚸(frontend) explain camera-in-use failures on the join screen
+
 ## [1.27.0] - 2026-08-14
 
 ### Changed
diff --git a/src/frontend/src/features/analytics/telemetry.ts b/src/frontend/src/features/analytics/telemetry.ts
index e208490d..79e454ae 100644
--- a/src/frontend/src/features/analytics/telemetry.ts
+++ b/src/frontend/src/features/analytics/telemetry.ts
@@ -137,6 +137,7 @@ export const captureMediaEvent = async (
     | 'media-device-topology'
     | 'media-device-success'
     | 'device-not-found'
+    | 'device-in-use'
     | 'permissions-denied'
     | 'screen-share-permission-denied'
     | 'silent-mic-detected'
diff --git a/src/frontend/src/features/rooms/components/Join.tsx b/src/frontend/src/features/rooms/components/Join.tsx
index caaffd39..663d7ff5 100644
--- a/src/frontend/src/features/rooms/components/Join.tsx
+++ b/src/frontend/src/features/rooms/components/Join.tsx
@@ -28,6 +28,7 @@ import {
   userChoicesStore,
 } from '@/stores/userChoices'
 import { useCannotUseDevice } from '../livekit/hooks/useCannotUseDevice'
+import { useDeviceInUse } from '../livekit/hooks/useDeviceInUse'
 import { useDeviceMissing } from '../livekit/hooks/useDeviceMissing'
 import { useJoinTracks } from '../livekit/hooks/useJoinTracks'
 import { SilentMicDetector } from './SilentMicDetector'
@@ -218,12 +219,14 @@ const switchTrackDevice =
 function getPreviewMessages({
   cameraFound,
   cameraDenied,
+  cameraInUse,
   micDenied,
   videoEnabled,
   videoStarted,
 }: {
   cameraFound: boolean
   cameraDenied: boolean
+  cameraInUse: boolean
   micDenied: boolean
   videoEnabled: boolean
   videoStarted: boolean
@@ -235,6 +238,9 @@ function getPreviewMessages({
     const key = micDenied ? 'cameraAndMicNotGranted' : 'cameraNotGranted'
     return { hint: key, permissionsButtonLabel: key }
   }
+  if (cameraInUse) {
+    return { hint: 'cameraInUse', permissionsButtonLabel: null }
+  }
   if (!videoEnabled) {
     return { hint: 'cameraDisabled', permissionsButtonLabel: null }
   }
@@ -328,18 +334,20 @@ const VideoPreview = ({
   const cameraDenied = useCannotUseDevice('videoinput')
   const micDenied = useCannotUseDevice('audioinput')
   const cameraMissing = useDeviceMissing('videoinput')
+  const cameraInUse = useDeviceInUse('videoinput')
 
   const { videoEl, videoStarted } = useAttachedVideo(videoTrack, videoEnabled)
 
   const { hint, permissionsButtonLabel } = getPreviewMessages({
     cameraFound: !cameraMissing,
     cameraDenied,
+    cameraInUse,
     micDenied,
     videoEnabled,
     videoStarted,
   })
 
-  const isError = cameraMissing || cameraDenied
+  const isError = cameraMissing || cameraDenied || cameraInUse
 
   return (
     <div className={styles.previewFrame}>
diff --git a/src/frontend/src/features/rooms/livekit/components/controls/Device/ToggleDevice.tsx b/src/frontend/src/features/rooms/livekit/components/controls/Device/ToggleDevice.tsx
index 23b9f201..be5e67fa 100644
--- a/src/frontend/src/features/rooms/livekit/components/controls/Device/ToggleDevice.tsx
+++ b/src/frontend/src/features/rooms/livekit/components/controls/Device/ToggleDevice.tsx
@@ -20,6 +20,7 @@ import { openPermissionsDialog } from '@/stores/permissions'
 import { openSilentMicDialog, silentMicStore } from '@/stores/silentMic'
 import { useSnapshot } from 'valtio'
 import { useCannotUseDevice } from '../../../hooks/useCannotUseDevice'
+import { useDeviceInUse } from '../../../hooks/useDeviceInUse'
 import { useDeviceMissing } from '../../../hooks/useDeviceMissing'
 import { requestDevicePermission } from '../../../hooks/useJoinTracks'
 import { useDeviceIcons } from '../../../hooks/useDeviceIcons'
@@ -97,21 +98,23 @@ export const ToggleDevice = <T extends ToggleSource>({
   const deviceIcons = useDeviceIcons(kind)
   const cannotUseDevice = useCannotUseDevice(kind)
   const deviceMissing = useDeviceMissing(kind)
+  const deviceInUse = useDeviceInUse(kind)
   const { status: silentMicStatus } = useSnapshot(silentMicStore)
   const silentMicWarning =
     kind === 'audioinput' &&
     silentMicStatus === 'silent' &&
     !cannotUseDevice &&
-    !deviceMissing
+    !deviceMissing &&
+    !deviceInUse
   const deviceShortcut = useDeviceShortcut(kind)
   const announce = useScreenReaderAnnounce()
 
   const isRequestingPermission = useRef(false)
-  const [showDeviceNotFound, setShowDeviceNotFound] = useState(false)
+  const [alertError, setAlertError] = useState<MediaDeviceFailure | null>(null)
 
   const onPress = async () => {
     if (!enabled && deviceMissing) {
-      setShowDeviceNotFound(true)
+      setAlertError(MediaDeviceFailure.NotFound)
       return
     }
     if (!cannotUseDevice) {
@@ -185,10 +188,18 @@ export const ToggleDevice = <T extends ToggleSource>({
         <PermissionNeededButton
           tooltip={deviceMissing ? t(`deviceNotFound.${kind}`) : undefined}
           onPress={
-            deviceMissing ? () => setShowDeviceNotFound(true) : undefined
+            deviceMissing
+              ? () => setAlertError(MediaDeviceFailure.NotFound)
+              : undefined
           }
         />
       )}
+      {deviceInUse && (
+        <PermissionNeededButton
+          tooltip={t(`deviceInUse.${kind}`)}
+          onPress={() => setAlertError(MediaDeviceFailure.DeviceInUse)}
+        />
+      )}
       {silentMicWarning && (
         <PermissionNeededButton
           tooltip={t('tooltip', { keyPrefix: 'silentMic' })}
@@ -207,9 +218,11 @@ export const ToggleDevice = <T extends ToggleSource>({
         tooltip={
           deviceMissing
             ? t(`deviceNotFound.${kind}`)
-            : cannotUseDevice
-              ? t('tooltip', { keyPrefix: 'permissionsButton' })
-              : toggleLabel
+            : deviceInUse
+              ? t(`deviceInUse.${kind}`)
+              : cannotUseDevice
+                ? t('tooltip', { keyPrefix: 'permissionsButton' })
+                : toggleLabel
         }
         {...computedToggleButtonProps}
         {...overrideToggleButtonProps}
@@ -217,9 +230,9 @@ export const ToggleDevice = <T extends ToggleSource>({
         <Icon />
       </ToggleButton>
       <MediaDeviceErrorAlert
-        error={showDeviceNotFound ? MediaDeviceFailure.NotFound : null}
+        error={alertError}
         kind={kind}
-        onClose={() => setShowDeviceNotFound(false)}
+        onClose={() => setAlertError(null)}
       />
     </div>
   )
diff --git a/src/frontend/src/features/rooms/livekit/hooks/useDeviceInUse.ts b/src/frontend/src/features/rooms/livekit/hooks/useDeviceInUse.ts
new file mode 100644
index 00000000..8cca93e1
--- /dev/null
+++ b/src/frontend/src/features/rooms/livekit/hooks/useDeviceInUse.ts
@@ -0,0 +1,15 @@
+import { useSnapshot } from 'valtio'
+import { deviceInUseStore } from '@/stores/deviceInUse'
+import { PERMISSION_BY_DEVICE_KIND } from '@/stores/permissions'
+import { useCannotUseDevice } from './useCannotUseDevice'
+import { useDeviceMissing } from './useDeviceMissing'
+
+export const useDeviceInUse = (kind: MediaDeviceKind): boolean => {
+  const inUse = useSnapshot(deviceInUseStore)
+  const cannotUseDevice = useCannotUseDevice(kind)
+  const deviceMissing = useDeviceMissing(kind)
+
+  const permissionKind = PERMISSION_BY_DEVICE_KIND[kind]
+  if (!permissionKind || cannotUseDevice || deviceMissing) return false
+  return inUse[permissionKind]
+}
diff --git a/src/frontend/src/features/rooms/livekit/hooks/useJoinTracks.ts b/src/frontend/src/features/rooms/livekit/hooks/useJoinTracks.ts
index 4192c837..d7dd2943 100644
--- a/src/frontend/src/features/rooms/livekit/hooks/useJoinTracks.ts
+++ b/src/frontend/src/features/rooms/livekit/hooks/useJoinTracks.ts
@@ -18,6 +18,7 @@ import {
   noteSystemPermissionDenied,
   type PermissionKind,
 } from '@/stores/permissions'
+import { clearDeviceInUse, noteDeviceInUse } from '@/stores/deviceInUse'
 import { getOS } from '@/utils/os'
 import { captureMediaEvent, reportError } from '@/features/analytics/telemetry'
 import {
@@ -89,7 +90,15 @@ const onMediaPermissionError = (
     return
   }
 
-  // "Other" and "Device in use" are still reported as errors, as they are not handled on the join screen.
+  if (
+    MediaDeviceFailure.getFailure(e) === MediaDeviceFailure.DeviceInUse &&
+    path === 'join_preview'
+  ) {
+    noteDeviceInUse(kind)
+    void captureMediaEvent('device-in-use', { path, kind, os: getOS() })
+    return
+  }
+
   reportError(
     path === 'room' ? 'room_media_failure' : 'join_preview_failure',
     e,
@@ -97,6 +106,11 @@ const onMediaPermissionError = (
   )
 }
 
+const noteDeviceReady = (kind?: PermissionKind) => {
+  noteGumSuccess(kind)
+  clearDeviceInUse(kind)
+}
+
 // Module-level: effect dependencies, must be referentially stable.
 const disableAudio = () => saveAudioInputEnabled(false)
 const disableVideo = () => saveVideoInputEnabled(false)
@@ -114,7 +128,7 @@ export const requestDevicePermission = async (
         ? await createLocalAudioTrack()
         : await createLocalVideoTrack()
     track.stop()
-    noteGumSuccess(PERMISSION_KIND[kind])
+    noteDeviceReady(PERMISSION_KIND[kind])
     return true
   } catch (error) {
     onMediaPermissionError(error as Error, PERMISSION_KIND[kind], path)
@@ -158,7 +172,7 @@ function useWarmupPermissions(): WarmupState {
             video: true,
           })
         )
-        noteGumSuccess()
+        noteDeviceReady()
         bothReady()
       } catch (error) {
         if (
@@ -180,7 +194,7 @@ function useWarmupPermissions(): WarmupState {
           .getUserMedia({ audio: true })
           .then((stream) => {
             stopAll(stream)
-            noteGumSuccess('microphone')
+            noteDeviceReady('microphone')
           })
           .catch((e) => onMediaPermissionError(e as Error, 'microphone'))
           .finally(() =>
@@ -190,7 +204,7 @@ function useWarmupPermissions(): WarmupState {
           .getUserMedia({ video: true })
           .then((stream) => {
             stopAll(stream)
-            noteGumSuccess('camera')
+            noteDeviceReady('camera')
           })
           .catch((e) => onMediaPermissionError(e as Error, 'camera'))
           .finally(() =>
@@ -227,7 +241,7 @@ function useLocalTrack<T extends LocalAudioTrack | LocalVideoTrack>({
     let cancelled = false
     create()
       .then((newTrack) => {
-        noteGumSuccess(permissionKind)
+        noteDeviceReady(permissionKind)
         if (cancelled) {
           newTrack.stop()
           return
@@ -291,6 +305,8 @@ export function useJoinTracks(): {
 
   const { audioReady, videoReady } = useWarmupPermissions()
 
+  useEffect(() => () => clearDeviceInUse(), [])
+
   const createAudio = useCallback(
     () =>
       createLocalAudioTrack({
diff --git a/src/frontend/src/locales/de/rooms.json b/src/frontend/src/locales/de/rooms.json
index bdacc707..f376255e 100644
--- a/src/frontend/src/locales/de/rooms.json
+++ b/src/frontend/src/locales/de/rooms.json
@@ -16,6 +16,10 @@
       "videoinput": "Keine Kamera erkannt. Prüfe, ob sie richtig angeschlossen ist.",
       "audioinput": "Kein Mikrofon erkannt. Prüfe, ob es richtig angeschlossen ist."
     },
+    "deviceInUse": {
+      "videoinput": "Kamera nicht verfügbar: Sie wird wahrscheinlich von einer anderen App oder einem anderen Tab verwendet.",
+      "audioinput": "Mikrofon nicht verfügbar: Es wird wahrscheinlich von einer anderen App oder einem anderen Tab verwendet."
+    },
     "settings": {
       "audio": "Audioeinstellungen",
       "video": "Videoeinstellungen"
@@ -67,6 +71,7 @@
     },
     "cameraDisabled": "Kamera ist deaktiviert.",
     "cameraNotFound": "Keine Kamera erkannt. Prüfe, ob sie richtig angeschlossen ist.",
+    "cameraInUse": "Deine Kamera ist nicht verfügbar. Sie wird wahrscheinlich von einer anderen App oder einem anderen Tab verwendet.",
     "cameraStarting": "Kamera wird gestartet…",
     "cameraNotGranted": "Möchtest du, dass andere dich während des Meetings sehen können?",
     "cameraAndMicNotGranted": "Möchtest du, dass andere dich während des Meetings sehen und hören können?",
diff --git a/src/frontend/src/locales/en/rooms.json b/src/frontend/src/locales/en/rooms.json
index 1c48fd80..22735163 100644
--- a/src/frontend/src/locales/en/rooms.json
+++ b/src/frontend/src/locales/en/rooms.json
@@ -16,6 +16,10 @@
       "videoinput": "No camera detected. Check that it is properly wired.",
       "audioinput": "No microphone detected. Check that it is properly wired."
     },
+    "deviceInUse": {
+      "videoinput": "Camera unavailable: it is probably in use by another application or browser tab.",
+      "audioinput": "Microphone unavailable: it is probably in use by another application or browser tab."
+    },
     "settings": {
       "audio": "Audio settings",
       "video": "Video settings"
@@ -67,6 +71,7 @@
     },
     "cameraDisabled": "Camera is disabled.",
     "cameraNotFound": "No camera detected. Check that it is properly plugged in.",
+    "cameraInUse": "Your camera is unavailable. It is probably being used by another application or browser tab.",
     "cameraStarting": "Camera is starting…",
     "cameraNotGranted": "Would you like others to be able to see you during the meeting?",
     "cameraAndMicNotGranted": "Would you like others to be able to see and hear you during the meeting?",
diff --git a/src/frontend/src/locales/fr/rooms.json b/src/frontend/src/locales/fr/rooms.json
index 9091d5a5..4de935b3 100644
--- a/src/frontend/src/locales/fr/rooms.json
+++ b/src/frontend/src/locales/fr/rooms.json
@@ -16,6 +16,10 @@
       "videoinput": "Aucune caméra détectée. Vérifiez qu'elle est bien branchée.",
       "audioinput": "Aucun microphone détecté. Vérifiez qu'il est bien branché."
     },
+    "deviceInUse": {
+      "videoinput": "Caméra indisponible : elle est probablement utilisée par une autre application ou un autre onglet.",
+      "audioinput": "Microphone indisponible : il est probablement utilisé par une autre application ou un autre onglet."
+    },
     "settings": {
       "audio": "Paramètres audio",
       "video": "Paramètres video"
@@ -67,6 +71,7 @@
     },
     "cameraDisabled": "La caméra est désactivée.",
     "cameraNotFound": "Aucune caméra détectée. Vérifiez qu'elle est bien branchée.",
+    "cameraInUse": "Votre caméra n'est pas disponible. Elle est probablement utilisée par une autre application ou un autre onglet.",
     "cameraStarting": "La caméra va démarrer…",
     "cameraNotGranted": "Souhaitez-vous que les autres puissent vous voir pendant la réunion ?",
     "cameraAndMicNotGranted": "Souhaitez-vous que les autres puissent vous voir et vous entendre pendant la réunion ?",
diff --git a/src/frontend/src/locales/nl/rooms.json b/src/frontend/src/locales/nl/rooms.json
index 36fff7dc..239f3641 100644
--- a/src/frontend/src/locales/nl/rooms.json
+++ b/src/frontend/src/locales/nl/rooms.json
@@ -16,6 +16,10 @@
       "videoinput": "Geen camera gedetecteerd. Controleer of deze goed is aangesloten.",
       "audioinput": "Geen microfoon gedetecteerd. Controleer of deze goed is aangesloten."
     },
+    "deviceInUse": {
+      "videoinput": "Camera niet beschikbaar: deze wordt waarschijnlijk gebruikt door een andere toepassing of een ander tabblad.",
+      "audioinput": "Microfoon niet beschikbaar: deze wordt waarschijnlijk gebruikt door een andere toepassing of een ander tabblad."
+    },
     "settings": {
       "audio": "Audio-instellingen",
       "video": "Video-instellingen"
@@ -67,6 +71,7 @@
     },
     "cameraDisabled": "Camera is uitgeschakeld.",
     "cameraNotFound": "Geen camera gedetecteerd. Controleer of deze goed is aangesloten.",
+    "cameraInUse": "Je camera is niet beschikbaar. Deze wordt waarschijnlijk gebruikt door een andere toepassing of een ander tabblad.",
     "cameraStarting": "Camera wordt ingeschakeld…",
     "cameraNotGranted": "Wilt u dat anderen u tijdens de vergadering kunnen zien?",
     "cameraAndMicNotGranted": "Wilt u dat anderen u tijdens de vergadering kunnen zien en horen?",
diff --git a/src/frontend/src/stores/deviceInUse.ts b/src/frontend/src/stores/deviceInUse.ts
new file mode 100644
index 00000000..db610a42
--- /dev/null
+++ b/src/frontend/src/stores/deviceInUse.ts
@@ -0,0 +1,21 @@
+import { proxy } from 'valtio'
+import type { PermissionKind } from './permissions'
+
+export const deviceInUseStore = proxy<Record<PermissionKind, boolean>>({
+  camera: false,
+  microphone: false,
+})
+
+const ALL_KINDS: PermissionKind[] = ['camera', 'microphone']
+
+export const noteDeviceInUse = (kind?: PermissionKind) => {
+  for (const k of kind ? [kind] : ALL_KINDS) {
+    deviceInUseStore[k] = true
+  }
+}
+
+export const clearDeviceInUse = (kind?: PermissionKind) => {
+  for (const k of kind ? [kind] : ALL_KINDS) {
+    deviceInUseStore[k] = false
+  }
+}