diff --git a/src/release-sync.ts b/src/release-sync.ts
index 2911427..7a2f647 100644
--- a/src/release-sync.ts
+++ b/src/release-sync.ts
@@ -216,6 +216,18 @@ async function listSyncedVersions(prisma: PrismaClient, type: ReleaseType): Prom
   return new Set(releases.map(release => release.version));
 }
 
+async function releaseExists(
+  prisma: PrismaClient,
+  type: ReleaseType,
+  version: string,
+): Promise<boolean> {
+  const release = await prisma.release.findUnique({
+    where: { version_type: { version, type } },
+    select: { id: true },
+  });
+  return release !== null;
+}
+
 function isUniqueViolation(error: unknown): boolean {
   return (
     error instanceof Prisma.PrismaClientKnownRequestError && error.code === "P2002"
@@ -279,8 +291,10 @@ async function createRelease(
     });
   } catch (error) {
     // Another API instance can win the race between the version listing and
-    // this insert. The row it wrote is the one we wanted, so treat it as synced.
-    if (isUniqueViolation(error)) {
+    // this insert, in which case the row it wrote is the one we wanted. Any
+    // other unique violation (a stale id sequence after a data import, say)
+    // leaves no row and is a real failure.
+    if (isUniqueViolation(error) && (await releaseExists(clients.prisma, type, version))) {
       console.log(`[sync-releases] ${type} ${version}: created concurrently elsewhere, skipping`);
       return "already-synced";
     }
@@ -326,9 +340,13 @@ export async function syncReleases(
     ]);
 
     for (const version of versions) {
+      // Name the release in any failure, whichever step raised it, so the
+      // scheduled run log does not need to be traced back to a version.
       const outcome = synced.has(version)
         ? "already-synced"
-        : await createRelease(clients, config, decide, type, version);
+        : await createRelease(clients, config, decide, type, version).catch((error: unknown) => {
+            throw new Error(`[sync-releases] ${type} ${version}: sync failed`, { cause: error });
+          });
       stats[outcome]++;
 
       if (outcome === "aborted") {
diff --git a/test/sync-releases.test.ts b/test/sync-releases.test.ts
index 51b3fbd..aa29e18 100644
--- a/test/sync-releases.test.ts
+++ b/test/sync-releases.test.ts
@@ -4,7 +4,7 @@ import {
   ListObjectsV2Command,
   S3Client,
 } from "@aws-sdk/client-s3";
-import { PrismaClient } from "@prisma/client";
+import { Prisma, PrismaClient } from "@prisma/client";
 import { afterEach, describe, expect, beforeEach, it, vi } from "vitest";
 
 import {
@@ -376,6 +376,7 @@ describe("syncReleases", () => {
     const racingPrisma = {
       release: {
         findMany: async () => [],
+        findUnique: (args: unknown) => testPrisma.release.findUnique(args as any),
         create: (args: unknown) => testPrisma.release.create(args as any),
       },
     } as unknown as PrismaClient;
@@ -392,6 +393,40 @@ describe("syncReleases", () => {
     });
     expect(release.url).toBe("https://cdn.test.com/other-instance");
   });
+
+  it("fails on a unique violation that left no release row behind", async () => {
+    const version = "9.9.9";
+    mockS3ListVersions("app", [version]);
+    mockS3HashFile("app", version, "app-hash");
+
+    // A stale id sequence (a database restored from a dump) makes the insert
+    // fail on the primary key with the same error code as the race above,
+    // but no row for this version exists afterwards.
+    const stalePrisma = {
+      release: {
+        findMany: async () => [],
+        findUnique: async () => null,
+        create: async () => {
+          throw new Prisma.PrismaClientKnownRequestError("Unique constraint failed", {
+            code: "P2002",
+            clientVersion: "test",
+            meta: { target: ["id"] },
+          });
+        },
+      },
+    } as unknown as PrismaClient;
+
+    await expect(
+      syncReleases(
+        { prisma: stalePrisma, s3Client: syncS3Client },
+        { bucketName: SYNC_BUCKET, baseUrl: SYNC_BASE_URL },
+        createAtDefaultRollout,
+      ),
+    ).rejects.toMatchObject({
+      message: "[sync-releases] app 9.9.9: sync failed",
+      cause: expect.objectContaining({ code: "P2002" }),
+    });
+  });
 });
 
 describe("scheduleReleaseSync", () => {