diff --git a/apps/bot/src/lib/safe-remove-job.ts b/apps/bot/src/lib/safe-remove-job.ts
index b785218..2a65889 100644
--- a/apps/bot/src/lib/safe-remove-job.ts
+++ b/apps/bot/src/lib/safe-remove-job.ts
@@ -5,6 +5,8 @@ import { logger } from '../logger.js';
  * Removes a BullMQ job when present. Locked (active) jobs cannot be removed —
  * those errors are swallowed so callers can still schedule a replacement jobId
  * or rely on removeOnComplete after the worker finishes.
+ * Jobs that belong to a Job Scheduler must be removed via removeJobScheduler;
+ * direct remove is ignored here.
  */
 export async function safeRemoveBullJob(
   job: Job | null | undefined,
@@ -17,10 +19,14 @@ export async function safeRemoveBullJob(
     await job.remove();
   } catch (error) {
     const message = error instanceof Error ? error.message : String(error);
-    if (message.includes('locked') || message.includes('could not be removed')) {
+    if (
+      message.includes('locked') ||
+      message.includes('could not be removed') ||
+      message.includes('belongs to a job scheduler')
+    ) {
       logger.warn(
         { error, jobId: context?.jobId ?? job.id, label: context?.label },
-        'BullMQ job is locked; skipping remove'
+        'BullMQ job could not be removed directly; skipping'
       );
       return;
     }
diff --git a/apps/bot/src/modules/scheduler/service.ts b/apps/bot/src/modules/scheduler/service.ts
index 52274ee..bebf892 100644
--- a/apps/bot/src/modules/scheduler/service.ts
+++ b/apps/bot/src/modules/scheduler/service.ts
@@ -78,6 +78,58 @@ export function scheduleJobId(scheduleId: string): string {
   return `schedule-${scheduleId}`;
 }
 
+/** BullMQ delayed instance ids look like `repeat:{schedulerId}:{millis}`. */
+const REPEAT_INSTANCE_ID_RE = /^repeat:(.+):(\d+)$/;
+
+function collectSchedulerIds(scheduleId: string, jobId: string | null | undefined): string[] {
+  const ids = new Set<string>();
+  ids.add(scheduleJobId(scheduleId));
+  if (!jobId) {
+    return [...ids];
+  }
+
+  const repeatMatch = jobId.match(REPEAT_INSTANCE_ID_RE);
+  if (repeatMatch?.[1]) {
+    ids.add(repeatMatch[1]);
+  } else if (!jobId.startsWith('repeat:')) {
+    ids.add(jobId);
+  }
+  return [...ids];
+}
+
+async function removeScheduleJobSchedulers(
+  queue: typeof scheduleQueue,
+  scheduleId: string,
+  jobId: string | null | undefined
+): Promise<void> {
+  for (const schedulerId of collectSchedulerIds(scheduleId, jobId)) {
+    try {
+      await queue.removeJobScheduler(schedulerId);
+    } catch (error) {
+      logger.warn({ schedulerId, error }, 'Failed to remove schedule job scheduler');
+    }
+  }
+
+  // Legacy / hash-keyed schedulers: match by payload scheduleId.
+  try {
+    const schedulers = await queue.getJobSchedulers();
+    for (const scheduler of schedulers) {
+      const data = scheduler.template?.data as { scheduleId?: string } | undefined;
+      if (data?.scheduleId !== scheduleId) {
+        continue;
+      }
+      const id = scheduler.id ?? scheduler.key;
+      try {
+        await queue.removeJobScheduler(id);
+      } catch (error) {
+        logger.warn({ schedulerId: id, error }, 'Failed to remove matched schedule job scheduler');
+      }
+    }
+  } catch (error) {
+    logger.warn({ scheduleId, error }, 'Failed to scan job schedulers for schedule');
+  }
+}
+
 function isValidCron(pattern: string): boolean {
   const parts = pattern.trim().split(/\s+/);
   return parts.length >= 5 && parts.length <= 6;
@@ -230,25 +282,36 @@ export async function removeScheduleJob(
   jobId: string | null,
   options?: { scheduleId?: string; cron?: string | null }
 ): Promise<void> {
-  const schedulerId = options?.scheduleId ? scheduleJobId(options.scheduleId) : jobId;
-  if (schedulerId && options?.cron) {
-    try {
-      await scheduleQueue.removeJobScheduler(schedulerId);
-    } catch (error) {
-      logger.warn({ schedulerId, error }, 'Failed to remove schedule job scheduler');
+  if (options?.scheduleId) {
+    await removeScheduleJobSchedulers(scheduleQueue, options.scheduleId, jobId);
+  } else if (options?.cron && jobId) {
+    // Best-effort for callers without scheduleId: extract scheduler from repeat instance id.
+    for (const schedulerId of collectSchedulerIds('unknown', jobId)) {
+      if (schedulerId === 'schedule-unknown') {
+        continue;
+      }
+      try {
+        await scheduleQueue.removeJobScheduler(schedulerId);
+      } catch (error) {
+        logger.warn({ schedulerId, error }, 'Failed to remove schedule job scheduler');
+      }
     }
   }
 
-  const candidateIds = new Set<string>();
-  if (jobId) {
-    candidateIds.add(jobId);
+  // One-shot delayed jobs only — never job.remove() on repeat:* scheduler children.
+  const oneShotIds = new Set<string>();
+  if (jobId && !jobId.startsWith('repeat:')) {
+    oneShotIds.add(jobId);
   }
-  if (schedulerId) {
-    candidateIds.add(schedulerId);
+  if (options?.scheduleId) {
+    oneShotIds.add(scheduleJobId(options.scheduleId));
   }
 
-  for (const id of candidateIds) {
+  for (const id of oneShotIds) {
     const job = await scheduleQueue.getJob(id);
+    if (job?.id && String(job.id).startsWith('repeat:')) {
+      continue;
+    }
     await safeRemoveBullJob(job, { label: 'schedule', jobId: id });
   }
 }
diff --git a/apps/webui/src/lib/module-configs/scheduler.ts b/apps/webui/src/lib/module-configs/scheduler.ts
index 0ba9ed9..7db0fe5 100644
--- a/apps/webui/src/lib/module-configs/scheduler.ts
+++ b/apps/webui/src/lib/module-configs/scheduler.ts
@@ -48,6 +48,81 @@ function scheduleJobId(scheduleId: string): string {
   return `schedule-${scheduleId}`;
 }
 
+/** BullMQ delayed instance ids look like `repeat:{schedulerId}:{millis}`. */
+const REPEAT_INSTANCE_ID_RE = /^repeat:(.+):(\d+)$/;
+
+function collectSchedulerIds(scheduleId: string, jobId: string | null | undefined): string[] {
+  const ids = new Set<string>();
+  ids.add(scheduleJobId(scheduleId));
+  if (!jobId) {
+    return [...ids];
+  }
+
+  const repeatMatch = jobId.match(REPEAT_INSTANCE_ID_RE);
+  if (repeatMatch?.[1]) {
+    ids.add(repeatMatch[1]);
+  } else if (!jobId.startsWith('repeat:')) {
+    ids.add(jobId);
+  }
+  return [...ids];
+}
+
+async function removeQueueSchedulersForSchedule(
+  scheduleId: string,
+  jobId: string | null | undefined
+): Promise<void> {
+  const queue = getScheduleQueue();
+
+  for (const schedulerId of collectSchedulerIds(scheduleId, jobId)) {
+    try {
+      await queue.removeJobScheduler(schedulerId);
+    } catch {
+      // Already gone or legacy key — keep trying other candidates.
+    }
+  }
+
+  try {
+    const schedulers = await queue.getJobSchedulers();
+    for (const scheduler of schedulers) {
+      const data = scheduler.template?.data as { scheduleId?: string } | undefined;
+      if (data?.scheduleId !== scheduleId) {
+        continue;
+      }
+      const id = scheduler.id ?? scheduler.key;
+      try {
+        await queue.removeJobScheduler(id);
+      } catch {
+        // ignore
+      }
+    }
+  } catch {
+    // ignore scan failures
+  }
+
+  // Older BullMQ repeatables (pre job-scheduler API).
+  try {
+    const repeatables = await queue.getRepeatableJobs();
+    for (const repeatable of repeatables) {
+      const matchesId =
+        repeatable.id === scheduleJobId(scheduleId) ||
+        (jobId != null &&
+          (repeatable.key === jobId ||
+            (REPEAT_INSTANCE_ID_RE.test(jobId) &&
+              repeatable.key.includes(jobId.match(REPEAT_INSTANCE_ID_RE)?.[1] ?? ''))));
+      if (!matchesId) {
+        continue;
+      }
+      try {
+        await queue.removeRepeatableByKey(repeatable.key);
+      } catch {
+        // ignore
+      }
+    }
+  } catch {
+    // ignore
+  }
+}
+
 export async function listScheduledMessagesDashboard(guildId: string): Promise<ScheduledMessageDashboard[]> {
   const schedules = await prisma.scheduledMessage.findMany({
     where: { guildId, enabled: true },
@@ -168,34 +243,33 @@ export async function deleteScheduledMessageDashboard(guildId: string, scheduleI
   }
 
   const queue = getScheduleQueue();
-  const schedulerId = scheduleJobId(existing.id);
+  await removeQueueSchedulersForSchedule(existing.id, existing.jobId);
 
-  if (existing.cron) {
-    try {
-      await queue.removeJobScheduler(schedulerId);
-    } catch {
-      // Scheduler may already be gone (legacy repeatables / one-shots).
-    }
+  // One-shot delayed jobs only — never job.remove() on repeat:* scheduler children
+  // (BullMQ throws code -8: belongs to a job scheduler).
+  const oneShotIds = new Set<string>();
+  oneShotIds.add(scheduleJobId(existing.id));
+  if (existing.jobId && !existing.jobId.startsWith('repeat:')) {
+    oneShotIds.add(existing.jobId);
   }
 
-  const candidateIds = new Set<string>();
-  candidateIds.add(schedulerId);
-  if (existing.jobId) {
-    candidateIds.add(existing.jobId);
-  }
-
-  for (const id of candidateIds) {
+  for (const id of oneShotIds) {
     const job = await queue.getJob(id);
-    if (!job) {
+    if (!job || (job.id && String(job.id).startsWith('repeat:'))) {
       continue;
     }
     try {
       await job.remove();
     } catch (error) {
       const message = error instanceof Error ? error.message : String(error);
-      if (!message.includes('locked') && !message.includes('could not be removed')) {
-        throw error;
+      if (
+        message.includes('locked') ||
+        message.includes('could not be removed') ||
+        message.includes('belongs to a job scheduler')
+      ) {
+        continue;
       }
+      throw error;
     }
   }
 
diff --git a/docs/PHASE-TRACKING.md b/docs/PHASE-TRACKING.md
index 7f8bd89..c5829d4 100644
--- a/docs/PHASE-TRACKING.md
+++ b/docs/PHASE-TRACKING.md
@@ -607,11 +607,13 @@
 - Dashboard: Timing-Mode (einmalig vs. Cron), naive `datetime-local` an Server, Fehlertexte i18n
 - Dark Mode: `color-scheme` + Input `text-foreground` für datetime-local Lesbarkeit
 - Shared Helper `resolveScheduleRunAt` / `guildLocalDateTimeToUtc`
+- Delete: Scheduler-Kinder (`repeat:…`) nicht per `job.remove()`; Legacy-Hash-IDs via `removeJobScheduler` / Scan
 
 ### Manuell testen
 
 - [ ] WebUI einmalig: Datum/Uhrzeit in Server-Zeitzone → Nachricht zur erwarteten lokalen Zeit
 - [ ] WebUI Cron `0 9 * * *` bei Europe/Berlin → ca. 09:00 Berlin (nicht UTC)
 - [ ] Cron-Plan löschen → keine weiteren Sends
+- [ ] Alten Cron-Eintrag (jobId `repeat:…`) im Dashboard löschen → kein API-Error -8
 - [ ] Dark Mode: Cron-Feld und datetime-local lesbar/bedienbar