diff --git a/apps/server/src/scheduledTasks/ScheduledTaskService.ts b/apps/server/src/scheduledTasks/ScheduledTaskService.ts
index afeb73de3df96..433959cd0ccae 100644
--- a/apps/server/src/scheduledTasks/ScheduledTaskService.ts
+++ b/apps/server/src/scheduledTasks/ScheduledTaskService.ts
@@ -334,9 +334,8 @@ function requireFutureOnce(
 }
 
 function errorMessage(error: unknown): string {
-  if (Cause.isCause(error)) return Cause.pretty(error);
-  if (error instanceof Error) return error.message;
-  return String(error);
+  const failure = Cause.isCause(error) ? Cause.squash(error) : error;
+  return failure instanceof Error ? failure.message : String(failure);
 }
 
 function webhookPath(taskId: string, token: string): string {
diff --git a/apps/server/src/scheduledTasks/ScheduledTaskService.webhook.test.ts b/apps/server/src/scheduledTasks/ScheduledTaskService.webhook.test.ts
index 6303b38c05ce6..90d2ccc329cbf 100644
--- a/apps/server/src/scheduledTasks/ScheduledTaskService.webhook.test.ts
+++ b/apps/server/src/scheduledTasks/ScheduledTaskService.webhook.test.ts
@@ -1399,6 +1399,7 @@ it.effect("start failures release both replay keys and relay claims for redelive
         yield* Queue.take(launches);
         assert.equal((yield* sql`SELECT * FROM scheduled_task_webhook_replay_keys`).length, 0);
         assert.equal((yield* sql`SELECT * FROM scheduled_task_webhook_relay_deliveries`).length, 0);
+        assert.equal((yield* service.list()).tasks[0]!.lastRunError, "injected start failure");
         const retry = yield* waitForSpan(
           service.triggerWebhook(request),
           "ScheduledTaskService.runWebhookDelivery",