diff --git a/graphql/resolvers/userDataCrud.test.js b/graphql/resolvers/userDataCrud.test.js
index 1fc6f0fe1..0356e9683 100644
--- a/graphql/resolvers/userDataCrud.test.js
+++ b/graphql/resolvers/userDataCrud.test.js
@@ -18,6 +18,7 @@ describe('User Data CRUD resolvers', () => {
     }
 
     prismaMock.user.update.mockResolvedValueOnce(userMock)
+    prismaMock.user.findFirst.mockResolvedValueOnce(null)
 
     expect(
       updateUserNames(
@@ -27,4 +28,24 @@ describe('User Data CRUD resolvers', () => {
       )
     ).resolves.toStrictEqual(userMock)
   })
+
+  it('Should not update the user username and name if username already used', async () => {
+    expect.assertions(1)
+
+    const userMock = {
+      username: mockUsername,
+      name: mockName
+    }
+
+    prismaMock.user.update.mockResolvedValueOnce(userMock)
+    prismaMock.user.findFirst.mockResolvedValueOnce(userMock)
+
+    expect(
+      updateUserNames(
+        null,
+        { username: mockUsername, mockName },
+        { req: { user: { id: 1 } } }
+      )
+    ).rejects.toEqual(Error('Username is already used'))
+  })
 })
diff --git a/graphql/resolvers/userDataCrud.ts b/graphql/resolvers/userDataCrud.ts
index ac3e78bfa..b4acac503 100644
--- a/graphql/resolvers/userDataCrud.ts
+++ b/graphql/resolvers/userDataCrud.ts
@@ -9,6 +9,16 @@ export const updateUserNames = withUserContainer<
 >(async (_, args, { req }) => {
   const { username, name } = args
 
+  const usernameAlreadyUsed = await prisma.user.findFirst({
+    where: {
+      username
+    }
+  })
+
+  if (usernameAlreadyUsed) {
+    throw new Error('Username is already used')
+  }
+
   const user = await prisma.user.update({
     where: {
       id: req.user!.id