diff --git a/src/commands/app/uninstall.test.ts b/src/commands/app/uninstall.test.ts
new file mode 100644
index 000000000..146241f2d
--- /dev/null
+++ b/src/commands/app/uninstall.test.ts
@@ -0,0 +1,44 @@
+import { describe, expect, it } from "@jest/globals";
+import { AxiosError, AxiosHeaders } from "axios";
+import { mapUninstallError } from "./uninstall.js";
+
+function axiosErrorWithStatus(status: number): AxiosError {
+  const headers = new AxiosHeaders();
+  const config = { headers };
+  return new AxiosError(
+    `Request failed with status code ${status}`,
+    "ERR_BAD_RESPONSE",
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    config as any,
+    {},
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    { status, data: {}, statusText: "", headers, config } as any,
+  );
+}
+
+describe("mapUninstallError", () => {
+  it("maps an HTTP 412 to a linked-primary-database hint", () => {
+    const original = axiosErrorWithStatus(412);
+    const mapped = mapUninstallError(original);
+
+    expect(mapped).toBeInstanceOf(Error);
+    expect((mapped as Error).message).toContain("cannot uninstall");
+    expect((mapped as Error).message).toContain("primary database");
+    // The original error is preserved as the cause and not swallowed.
+    expect((mapped as Error).cause).toBe(original);
+  });
+
+  it("passes through other Axios errors unchanged", () => {
+    const original = axiosErrorWithStatus(409);
+    const mapped = mapUninstallError(original);
+
+    expect(mapped).toBe(original);
+  });
+
+  it("passes through non-Axios errors unchanged", () => {
+    const original = new Error("something else");
+    const mapped = mapUninstallError(original);
+
+    expect(mapped).toBe(original);
+  });
+});
diff --git a/src/commands/app/uninstall.ts b/src/commands/app/uninstall.ts
index d25e0bdce..779a0e325 100644
--- a/src/commands/app/uninstall.ts
+++ b/src/commands/app/uninstall.ts
@@ -1,7 +1,28 @@
 import { assertStatus } from "@mittwald/api-client-commons";
+import axios from "axios";
 import { DeleteBaseCommand } from "../../lib/basecommands/DeleteBaseCommand.js";
 import { appInstallationArgs } from "../../lib/resources/app/flags.js";
 
+/**
+ * Maps an error raised while uninstalling an app installation to a more
+ * actionable one. The API answers with an HTTP 412 (Precondition Failed) when
+ * the app still has a linked _primary_ database; in that case we surface a
+ * clear hint instead of a raw Axios error. All other errors are passed through
+ * unchanged so they are not accidentally swallowed.
+ */
+export function mapUninstallError(err: unknown): unknown {
+  if (axios.isAxiosError(err) && err.response?.status === 412) {
+    return new Error(
+      "cannot uninstall: app has a linked primary database — " +
+        "unlink or repurpose it first (a primary database must be " +
+        "repurposed to custom or cache before it can be unlinked)",
+      { cause: err },
+    );
+  }
+
+  return err;
+}
+
 export default class Uninstall extends DeleteBaseCommand<typeof Uninstall> {
   static description = "Uninstall an app";
   static resourceName = "app installation";
@@ -12,10 +33,15 @@ export default class Uninstall extends DeleteBaseCommand<typeof Uninstall> {
 
   protected async deleteResource(): Promise<void> {
     const appInstallationId = await this.withAppInstallationId(Uninstall);
-    const response = await this.apiClient.app.uninstallAppinstallation({
-      appInstallationId,
-    });
 
-    assertStatus(response, 204);
+    try {
+      const response = await this.apiClient.app.uninstallAppinstallation({
+        appInstallationId,
+      });
+
+      assertStatus(response, 204);
+    } catch (err) {
+      throw mapUninstallError(err);
+    }
   }
 }
diff --git a/src/lib/basecommands/DeleteBaseCommand.test.tsx b/src/lib/basecommands/DeleteBaseCommand.test.tsx
new file mode 100644
index 000000000..347bab0a4
--- /dev/null
+++ b/src/lib/basecommands/DeleteBaseCommand.test.tsx
@@ -0,0 +1,97 @@
+import { beforeEach, describe, expect, it, jest } from "@jest/globals";
+
+/*
+ * Regression test for the bug where a failing deletion (e.g. an app uninstall
+ * rejected with HTTP 412) still printed "Process completed successfully" and
+ * exited with code 0. The command must instead surface the error via
+ * process.error() and exit with a non-zero code.
+ */
+
+const fakeStep = {
+  complete: jest.fn(),
+  error: jest.fn(),
+};
+
+const fakeProcess = {
+  start: jest.fn(),
+  addStep: jest.fn(() => fakeStep),
+  addConfirmation: jest.fn(async () => true),
+  addInfo: jest.fn(),
+  complete: jest.fn(async (_summary: unknown) => {}),
+  error: jest.fn(async (_err: unknown) => {}),
+};
+
+const makeProcessRenderer = jest.fn(() => fakeProcess);
+
+jest.unstable_mockModule("../../rendering/process/process_flags.js", () => ({
+  __esModule: true,
+  makeProcessRenderer,
+  processFlags: {},
+}));
+
+const { DeleteBaseCommand } = await import("./DeleteBaseCommand.js");
+
+class TestDelete extends DeleteBaseCommand<typeof TestDelete> {
+  static resourceName = "test resource";
+  public shouldThrow: unknown = undefined;
+
+  protected async deleteResource(): Promise<void> {
+    if (this.shouldThrow !== undefined) {
+      throw this.shouldThrow;
+    }
+  }
+}
+
+function makeInstance(): TestDelete {
+  const instance = Object.create(TestDelete.prototype) as TestDelete;
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  (instance as any).flags = { force: true };
+  return instance;
+}
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+async function runExec(instance: TestDelete): Promise<any> {
+  try {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    await (instance as any).exec();
+    return undefined;
+  } catch (err) {
+    return err;
+  }
+}
+
+describe("DeleteBaseCommand", () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it("reports success and does not exit non-zero when deletion succeeds", async () => {
+    const instance = makeInstance();
+
+    const thrown = await runExec(instance);
+
+    expect(fakeStep.complete).toHaveBeenCalled();
+    expect(fakeProcess.complete).toHaveBeenCalledTimes(1);
+    expect(fakeProcess.error).not.toHaveBeenCalled();
+    // no ux.exit() -> no thrown ExitError
+    expect(thrown).toBeUndefined();
+  });
+
+  it("surfaces the error and exits non-zero when deletion fails", async () => {
+    const instance = makeInstance();
+    const failure = new Error("boom");
+    instance.shouldThrow = failure;
+
+    const thrown = await runExec(instance);
+
+    // Must NOT falsely report success ...
+    expect(fakeProcess.complete).not.toHaveBeenCalled();
+    // ... must surface the actual error ...
+    expect(fakeStep.error).toHaveBeenCalledWith(failure);
+    expect(fakeProcess.error).toHaveBeenCalledWith(failure);
+    // ... and must exit with a non-zero code (ux.exit(1) throws an ExitError).
+    expect(thrown).toBeDefined();
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    expect((thrown as any).oclif?.exit).toBe(1);
+  });
+});
diff --git a/src/lib/basecommands/DeleteBaseCommand.tsx b/src/lib/basecommands/DeleteBaseCommand.tsx
index 129d2c3d6..8215b5ad8 100644
--- a/src/lib/basecommands/DeleteBaseCommand.tsx
+++ b/src/lib/basecommands/DeleteBaseCommand.tsx
@@ -7,7 +7,6 @@ import {
   processFlags,
 } from "../../rendering/process/process_flags.js";
 import { Success } from "../../rendering/react/components/Success.js";
-import { Text } from "ink";
 import React from "react";
 
 export abstract class DeleteBaseCommand<
@@ -56,7 +55,7 @@ export abstract class DeleteBaseCommand<
       );
     } catch (err) {
       deletingStep.error(err);
-      process.complete(<Text>Failed to delete {resourceName}</Text>);
+      await process.error(err);
       ux.exit(1);
     }
   }