# Clients experience sign-in issues on the B2CORE mobile app

## Problem

Clients may encounter various sign-in issues when using the mobile app on **iOS** or **Android**, such as:

* The **Sign In** button not responding
* Sessions closing immediately after sign-in
* Valid credentials not being accepted
* Biometric options (Face ID or fingerprint) not working

## Possible reasons

* Background processes interfering with the app
* Expired or corrupted session data
* Outdated app version or corrupted installation
* Device OS not updated
* Cache-related issues (for Android only)

## Solution

To resolve most sign-in issues:

{% stepper %}
{% step %}

#### Force close and reopen the app

Sometimes background processes cause unexpected issues. Fully close the app from recent apps, and then reopen it.
{% endstep %}

{% step %}

#### Sign out of the app and sign in again

If the session expires quickly, manually sign out of the app (if possible), and then sign in again.
{% endstep %}

{% step %}

#### Reinstall the app

* Uninstall the app.
* Download and reinstall it from **App Store** (iOS) or via the APK file (Android).
  {% endstep %}

{% step %}

#### Update the app

* Check for the latest version in the **App Store** (iOS) or via the APK file (Android).
* Install updates to ensure compatibility and bug fixes.
  {% endstep %}

{% step %}

#### Check for OS updates

* On iOS, go to **Settings** > **General** > **Software update**.
* On Android, go to **Settings** > **About phone** > **System update** (or **Software updates**, depending on your device).
* Install any available updates, as outdated OS versions can cause incompatibility.
  {% endstep %}

{% step %}

#### Clear app cache (for Android only)

Go to **Settings** > **Apps** > **{App name}** > **Storage** > **Clear cache**.
{% endstep %}
{% endstepper %}