diff --git a/apps/nextjs/src/app/[locale]/auth/invite/[id]/_registration-form.tsx b/apps/nextjs/src/app/[locale]/auth/invite/[id]/_registration-form.tsx
index e91e78de0..b1986f12c 100644
--- a/apps/nextjs/src/app/[locale]/auth/invite/[id]/_registration-form.tsx
+++ b/apps/nextjs/src/app/[locale]/auth/invite/[id]/_registration-form.tsx
@@ -44,10 +44,15 @@ export const RegistrationForm = ({ invite }: RegistrationFormProps) => {
           });
           router.push("/auth/login");
         },
-        onError() {
+        onError(error) {
+          const message =
+            error.data?.code === "CONFLICT"
+              ? t("error.usernameTaken")
+              : t("action.register.notification.error.message");
+
           showErrorNotification({
             title: t("action.register.notification.error.title"),
-            message: t("action.register.notification.error.message"),
+            message,
           });
         },
       },
diff --git a/apps/nextjs/src/app/[locale]/manage/users/[userId]/general/_components/_profile-form.tsx b/apps/nextjs/src/app/[locale]/manage/users/[userId]/general/_components/_profile-form.tsx
index 54f45526b..44ba9ddb7 100644
--- a/apps/nextjs/src/app/[locale]/manage/users/[userId]/general/_components/_profile-form.tsx
+++ b/apps/nextjs/src/app/[locale]/manage/users/[userId]/general/_components/_profile-form.tsx
@@ -22,16 +22,25 @@ export const UserProfileForm = ({ user }: UserProfileFormProps) => {
     async onSettled() {
       await revalidatePathActionAsync("/manage/users");
     },
-    onSuccess() {
+    onSuccess(_, variables) {
+      // Reset form initial values to reset dirty state
+      form.setInitialValues({
+        name: variables.name,
+        email: variables.email ?? "",
+      });
       showSuccessNotification({
         title: t("common.notification.update.success"),
         message: t("user.action.editProfile.notification.success.message"),
       });
     },
-    onError() {
+    onError(error) {
+      const message =
+        error.data?.code === "CONFLICT"
+          ? t("user.error.usernameTaken")
+          : t("user.action.editProfile.notification.error.message");
       showErrorNotification({
         title: t("common.notification.update.error"),
-        message: t("user.action.editProfile.notification.error.message"),
+        message,
       });
     },
   });
@@ -59,7 +68,7 @@ export const UserProfileForm = ({ user }: UserProfileFormProps) => {
         <TextInput label={t("user.field.email.label")} {...form.getInputProps("email")} />
 
         <Group justify="end">
-          <Button type="submit" color="teal" loading={isPending}>
+          <Button type="submit" color="teal" disabled={!form.isDirty()} loading={isPending}>
             {t("common.action.saveChanges")}
           </Button>
         </Group>
diff --git a/apps/nextjs/src/app/[locale]/manage/users/create/_components/create-user-stepper.tsx b/apps/nextjs/src/app/[locale]/manage/users/create/_components/create-user-stepper.tsx
index 5a27d206c..eadf51ddd 100644
--- a/apps/nextjs/src/app/[locale]/manage/users/create/_components/create-user-stepper.tsx
+++ b/apps/nextjs/src/app/[locale]/manage/users/create/_components/create-user-stepper.tsx
@@ -6,6 +6,7 @@ import { IconUserCheck } from "@tabler/icons-react";
 
 import { clientApi } from "@homarr/api/client";
 import { useZodForm } from "@homarr/form";
+import { showErrorNotification } from "@homarr/notifications";
 import { useScopedI18n } from "@homarr/translation/client";
 import { validation, z } from "@homarr/validation";
 import { createCustomErrorParams } from "@homarr/validation/form";
@@ -26,7 +27,16 @@ export const UserCreateStepperComponent = () => {
   const hasNext = active < stepperMax;
   const hasPrevious = active > 0;
 
-  const { mutateAsync, isPending } = clientApi.user.create.useMutation();
+  const { mutateAsync, isPending } = clientApi.user.create.useMutation({
+    onError(error) {
+      showErrorNotification({
+        autoClose: false,
+        id: "create-user-error",
+        title: t("step.error.title"),
+        message: error.message,
+      });
+    },
+  });
 
   const generalForm = useZodForm(
     z.object({
diff --git a/packages/api/src/router/user.ts b/packages/api/src/router/user.ts
index edffc2ae5..7d3fbd100 100644
--- a/packages/api/src/router/user.ts
+++ b/packages/api/src/router/user.ts
@@ -44,11 +44,23 @@ export const userRouter = createTRPCRouter({
       });
     }
 
+    if (!dbInvite || dbInvite.expirationDate < new Date()) {
+      throw new TRPCError({
+        code: "FORBIDDEN",
+        message: "Invalid invite",
+      });
+    }
+
+    await checkUsernameAlreadyTakenAndThrowAsync(ctx.db, input.username);
+
     await createUserAsync(ctx.db, input);
+
     // Delete invite as it's used
     await ctx.db.delete(invites).where(inviteWhere);
   }),
   create: publicProcedure.input(validation.user.create).mutation(async ({ ctx, input }) => {
+    await checkUsernameAlreadyTakenAndThrowAsync(ctx.db, input.username);
+
     await createUserAsync(ctx.db, input);
   }),
   setProfileImage: protectedProcedure
@@ -148,6 +160,8 @@ export const userRouter = createTRPCRouter({
       });
     }
 
+    await checkUsernameAlreadyTakenAndThrowAsync(ctx.db, input.name, input.id);
+
     const emailDirty = input.email && user.email !== input.email;
     await ctx.db
       .update(users)
@@ -227,12 +241,28 @@ const createUserAsync = async (db: Database, input: z.infer<typeof validation.us
   const salt = await createSaltAsync();
   const hashedPassword = await hashPasswordAsync(input.password, salt);
 
+  const username = input.username.toLowerCase();
+
   const userId = createId();
   await db.insert(schema.users).values({
     id: userId,
-    name: input.username,
+    name: username,
     email: input.email,
     password: hashedPassword,
     salt,
   });
 };
+
+const checkUsernameAlreadyTakenAndThrowAsync = async (db: Database, username: string, ignoreId?: string) => {
+  const user = await db.query.users.findFirst({
+    where: eq(users.name, username.toLowerCase()),
+  });
+
+  if (!user) return;
+  if (ignoreId && user.id === ignoreId) return;
+
+  throw new TRPCError({
+    code: "CONFLICT",
+    message: "Username already taken",
+  });
+};
diff --git a/packages/notifications/src/index.tsx b/packages/notifications/src/index.tsx
index f63139abe..071496b20 100644
--- a/packages/notifications/src/index.tsx
+++ b/packages/notifications/src/index.tsx
@@ -2,16 +2,14 @@ import type { NotificationData } from "@mantine/notifications";
 import { notifications } from "@mantine/notifications";
 import { IconCheck, IconX } from "@tabler/icons-react";
 
-type CommonNotificationProps = Pick<NotificationData, "title" | "message">;
-
-export const showSuccessNotification = (props: CommonNotificationProps) =>
+export const showSuccessNotification = (props: NotificationData) =>
   notifications.show({
     ...props,
     color: "teal",
     icon: <IconCheck size={20} />,
   });
 
-export const showErrorNotification = (props: CommonNotificationProps) =>
+export const showErrorNotification = (props: NotificationData) =>
   notifications.show({
     ...props,
     color: "red",
diff --git a/packages/translation/src/lang/en.ts b/packages/translation/src/lang/en.ts
index 757502ffb..3ba679d51 100644
--- a/packages/translation/src/lang/en.ts
+++ b/packages/translation/src/lang/en.ts
@@ -36,6 +36,9 @@ export default {
         label: "Previous password",
       },
     },
+    error: {
+      usernameTaken: "Username already taken",
+    },
     action: {
       login: {
         label: "Login",
@@ -1219,6 +1222,9 @@ export default {
             completed: {
               title: "User created",
             },
+            error: {
+              title: "User creation failed",
+            },
           },
           action: {
             createAnother: "Create another user",