diff --git a/src/main/debrid.ts b/src/main/debrid.ts
index 07785d3..00c5d8e 100644
--- a/src/main/debrid.ts
+++ b/src/main/debrid.ts
@@ -1897,7 +1897,7 @@ class MegaDebridClient {
           logger.info(`Mega-Debrid (API) unrestrict OK: ${apiResult.fileName}`);
           return apiResult;
         }
-        throw new Error("Mega-Debrid API: Login oder Unrestrict fehlgeschlagen");
+        throw new Error("Mega-Debrid API: Linkgenerierung lieferte kein Ergebnis");
       } catch (error) {
         const errorText = compactErrorText(error);
         if (signal?.aborted || (/aborted/i.test(errorText) && !/timeout/i.test(errorText))) {
@@ -2162,7 +2162,11 @@ class MegaDebridClient {
       return { fatal: true, cooldownMs: 0, message: errorText, category: "temporary" };
     }
 
-    if (/login|password|auth|credentials|unauthorized|forbidden/i.test(errorText) || /connectUser/i.test(errorText)) {
+    if (/token.?error|please log.?in/i.test(errorText)) {
+      return { fatal: false, cooldownMs: 15_000, message: errorText, category: "temporary" };
+    }
+
+    if (/bad.?login|incorrect.?(login|password)|invalid.?(login|password|credentials)|wrong.?password|unauthorized|forbidden|connectUser/i.test(errorText)) {
       return {
         fatal: false,
         cooldownMs: MEGA_DEBRID_INVALID_ACCOUNT_COOLDOWN_MS,
diff --git a/src/main/download-manager.ts b/src/main/download-manager.ts
index 304c267..a432331 100644
--- a/src/main/download-manager.ts
+++ b/src/main/download-manager.ts
@@ -7998,9 +7998,10 @@ export class DownloadManager extends EventEmitter {
   }
 
   private getSerializedValidatingLimit(provider: DebridProvider | null): number {
-    if (provider === "megadebrid-web") {
+    if (provider === "megadebrid-web" || provider === "megadebrid-api") {
+      const mode = provider === "megadebrid-web" ? "web" : "api";
       const usableAccounts = getAvailableMegaDebridAccounts(this.settings)
-        .filter((account) => !getMegaDebridAccountCooldownState(`${account.id}:web`))
+        .filter((account) => !getMegaDebridAccountCooldownState(`${account.id}:${mode}`))
         .length;
       return Math.max(1, usableAccounts);
     }
diff --git a/tests/debrid.test.ts b/tests/debrid.test.ts
index 670b366..844b2ce 100644
--- a/tests/debrid.test.ts
+++ b/tests/debrid.test.ts
@@ -1339,6 +1339,84 @@ describe("debrid service", () => {
     expect(getMegaDebridAccountCooldownState(`${getMegaDebridAccountId("user")}:api`)).toBeNull();
   });
 
+  it("does NOT slap a 60-minute 'invalid' cooldown on a working account when the API returns no result (transient)", async () => {
+    const settings = {
+      ...defaultSettings(),
+      token: "",
+      bestToken: "",
+      allDebridToken: "",
+      megaLogin: "user",
+      megaPassword: "pass",
+      megaCredentials: "user:pass",
+      megaDebridApiEnabled: true,
+      megaDebridWebEnabled: false,
+      providerPrimary: "megadebrid-api" as const,
+      providerSecondary: "none" as const,
+      providerTertiary: "none" as const,
+      autoProviderFallback: true
+    };
+
+    globalThis.fetch = (async (input: RequestInfo | URL): Promise<Response> => {
+      const url = typeof input === "string" ? input : input instanceof URL ? input.toString() : input.url;
+      if (url.includes("action=connectUser")) {
+        return new Response(JSON.stringify({ response_code: "ok", token: "tok", vip_end: Math.floor(Date.now() / 1000) + 999999 }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      if (url.includes("action=getLink")) {
+        return new Response(JSON.stringify({ response_code: "ok" }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      return new Response("not-found", { status: 404 });
+    }) as typeof fetch;
+
+    const service = new DebridService(settings);
+    const err = await service.unrestrictLink("https://rapidgator.net/file/no-result.rar.html").then(() => null, (e: unknown) => e);
+    expect(err).toBeTruthy();
+    expect(String(err)).not.toMatch(/Login oder Unrestrict/i);
+
+    const cooldown = getMegaDebridAccountCooldownState(`${getMegaDebridAccountId("user")}:api`);
+    if (cooldown) {
+      expect(cooldown.category).not.toBe("invalid");
+      expect(cooldown.remainingMs).toBeLessThan(5 * 60 * 1000);
+    }
+  });
+
+  it("treats a Mega-Debrid API 'Token error, please log-in' as a short transient cooldown, not invalid", async () => {
+    const settings = {
+      ...defaultSettings(),
+      token: "",
+      bestToken: "",
+      allDebridToken: "",
+      megaLogin: "user",
+      megaPassword: "pass",
+      megaCredentials: "user:pass",
+      megaDebridApiEnabled: true,
+      megaDebridWebEnabled: false,
+      providerPrimary: "megadebrid-api" as const,
+      providerSecondary: "none" as const,
+      providerTertiary: "none" as const,
+      autoProviderFallback: true
+    };
+
+    globalThis.fetch = (async (input: RequestInfo | URL): Promise<Response> => {
+      const url = typeof input === "string" ? input : input instanceof URL ? input.toString() : input.url;
+      if (url.includes("action=connectUser")) {
+        return new Response(JSON.stringify({ response_code: "ok", token: "tok", vip_end: Math.floor(Date.now() / 1000) + 999999 }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      if (url.includes("action=getLink")) {
+        return new Response(JSON.stringify({ response_code: "error_token", response_text: "Token error, please log-in" }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      return new Response("not-found", { status: 404 });
+    }) as typeof fetch;
+
+    const service = new DebridService(settings);
+    await service.unrestrictLink("https://rapidgator.net/file/token-collision.rar.html").then(() => null, (e: unknown) => e);
+
+    const cooldown = getMegaDebridAccountCooldownState(`${getMegaDebridAccountId("user")}:api`);
+    if (cooldown) {
+      expect(cooldown.category).not.toBe("invalid");
+      expect(cooldown.remainingMs).toBeLessThan(60 * 1000);
+    }
+  });
+
   it("uses Mega Web only when it is configured as a separate fallback provider", async () => {
     const settings = {
       ...defaultSettings(),
diff --git a/tests/download-manager.test.ts b/tests/download-manager.test.ts
index e6290e7..d59c1f0 100644
--- a/tests/download-manager.test.ts
+++ b/tests/download-manager.test.ts
@@ -6721,6 +6721,160 @@ describe("download manager", () => {
     await new Promise((resolve) => setTimeout(resolve, 150));
   });
 
+  it("serializes Mega-Debrid API conversions to one per account (no single-token hammering)", async () => {
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "rd-dm-"));
+    tempDirs.push(root);
+
+    let getLinkCalls = 0;
+    const pendingRejectors = new Set<(error: Error) => void>();
+    globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit): Promise<Response> => {
+      const url = typeof input === "string" ? input : input instanceof URL ? input.toString() : (input as Request).url;
+      if (url.includes("action=connectUser")) {
+        return new Response(JSON.stringify({ response_code: "ok", token: `tok-${getLinkCalls}-${url.length}` }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      if (url.includes("action=getLink")) {
+        getLinkCalls += 1;
+        const signal = init?.signal;
+        return await new Promise<Response>((_resolve, reject) => {
+          const rejector = (error: Error): void => {
+            signal?.removeEventListener("abort", onAbort);
+            pendingRejectors.delete(rejector);
+            reject(error);
+          };
+          const onAbort = (): void => { rejector(new Error("aborted:test-api")); };
+          if (signal?.aborted) { onAbort(); return; }
+          signal?.addEventListener("abort", onAbort, { once: true });
+          pendingRejectors.add(rejector);
+        });
+      }
+      return originalFetch(input, init);
+    }) as typeof fetch;
+
+    const manager = new DownloadManager(
+      {
+        ...defaultSettings(),
+        megaCredentials: "mega-user-a:pass-a\nmega-user-b:pass-b",
+        megaDebridApiEnabled: true,
+        megaDebridWebEnabled: false,
+        megaDebridPreferApi: true,
+        providerOrder: [],
+        providerPrimary: "megadebrid",
+        providerSecondary: "none",
+        providerTertiary: "none",
+        outputDir: path.join(root, "downloads"),
+        extractDir: path.join(root, "extract"),
+        autoExtract: false,
+        autoReconnect: false,
+        enableIntegrityCheck: false,
+        maxParallel: 6
+      },
+      emptySession(),
+      createStoragePaths(path.join(root, "state")),
+      {}
+    );
+
+    manager.addPackages([{
+      name: "mega-api-serialized",
+      links: [
+        "https://rapidgator.net/file/api-1.part1.rar.html",
+        "https://rapidgator.net/file/api-2.part2.rar.html",
+        "https://rapidgator.net/file/api-3.part3.rar.html"
+      ]
+    }]);
+
+    await manager.start();
+    await waitFor(() => getLinkCalls === 2, 10000);
+    await new Promise((resolve) => setTimeout(resolve, 250));
+
+    const items = Object.values(manager.getSnapshot().session.items);
+    expect(items.filter((item) => item.status === "validating")).toHaveLength(2);
+    expect(items.filter((item) => item.status === "queued")).toHaveLength(1);
+    expect(getLinkCalls).toBe(2);
+
+    manager.stop();
+    for (const reject of Array.from(pendingRejectors)) {
+      reject(new Error("aborted:test-api"));
+    }
+    await new Promise((resolve) => setTimeout(resolve, 150));
+  });
+
+  it("limits Mega-Debrid API conversions to one at a time with a single account", async () => {
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "rd-dm-"));
+    tempDirs.push(root);
+
+    let getLinkCalls = 0;
+    const pendingRejectors = new Set<(error: Error) => void>();
+    globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit): Promise<Response> => {
+      const url = typeof input === "string" ? input : input instanceof URL ? input.toString() : (input as Request).url;
+      if (url.includes("action=connectUser")) {
+        return new Response(JSON.stringify({ response_code: "ok", token: "tok-single" }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      if (url.includes("action=getLink")) {
+        getLinkCalls += 1;
+        const signal = init?.signal;
+        return await new Promise<Response>((_resolve, reject) => {
+          const rejector = (error: Error): void => {
+            signal?.removeEventListener("abort", onAbort);
+            pendingRejectors.delete(rejector);
+            reject(error);
+          };
+          const onAbort = (): void => { rejector(new Error("aborted:test-api")); };
+          if (signal?.aborted) { onAbort(); return; }
+          signal?.addEventListener("abort", onAbort, { once: true });
+          pendingRejectors.add(rejector);
+        });
+      }
+      return originalFetch(input, init);
+    }) as typeof fetch;
+
+    const manager = new DownloadManager(
+      {
+        ...defaultSettings(),
+        megaCredentials: "mega-user:mega-pass",
+        megaDebridApiEnabled: true,
+        megaDebridWebEnabled: false,
+        megaDebridPreferApi: true,
+        providerOrder: [],
+        providerPrimary: "megadebrid",
+        providerSecondary: "none",
+        providerTertiary: "none",
+        outputDir: path.join(root, "downloads"),
+        extractDir: path.join(root, "extract"),
+        autoExtract: false,
+        autoReconnect: false,
+        enableIntegrityCheck: false,
+        maxParallel: 6
+      },
+      emptySession(),
+      createStoragePaths(path.join(root, "state")),
+      {}
+    );
+
+    manager.addPackages([{
+      name: "mega-api-single",
+      links: [
+        "https://rapidgator.net/file/single-1.part1.rar.html",
+        "https://rapidgator.net/file/single-2.part2.rar.html",
+        "https://rapidgator.net/file/single-3.part3.rar.html"
+      ]
+    }]);
+
+    await manager.start();
+    await waitFor(() => getLinkCalls === 1, 10000);
+    await new Promise((resolve) => setTimeout(resolve, 250));
+
+    const items = Object.values(manager.getSnapshot().session.items);
+    expect(items.filter((item) => item.status === "validating")).toHaveLength(1);
+    expect(items.filter((item) => item.status === "queued")).toHaveLength(2);
+    expect(getLinkCalls).toBe(1);
+
+    manager.stop();
+    for (const reject of Array.from(pendingRejectors)) {
+      reject(new Error("aborted:test-api"));
+    }
+    await new Promise((resolve) => setTimeout(resolve, 150));
+  });
+
   it("shows the same AllDebrid countdown for all immediately free slots", async () => {
     const root = fs.mkdtempSync(path.join(os.tmpdir(), "rd-dm-"));
     tempDirs.push(root);