diff --git a/modules/openid/openid.module b/modules/openid/openid.module
index 7673de8..bc807d1 100644
--- a/modules/openid/openid.module
+++ b/modules/openid/openid.module
@@ -589,8 +589,14 @@ function openid_association($op_endpoint) {
  */
 function openid_authentication($response) {
   $identity = $response['openid.claimed_id'];
-
   $account = user_external_load($identity);
+
+  // Tries to load user account if user_external_load fails due to possibly
+  // incompletely stored OpenID identifier in the authmap.
+  if (!isset($account->uid)) {
+    $account = _openid_invalid_openid_transition($identity, $response);
+  }
+
   if (isset($account->uid)) {
     if (!variable_get('user_email_verification', TRUE) || $account->login) {
       // Check if user is blocked.
@@ -634,7 +640,7 @@ function openid_authentication($response) {
       drupal_set_message(t('Account registration using the information provided by your OpenID provider failed due to the reasons listed below. Complete the registration by filling out the form below. If you already have an account, you can <a href="@login">log in</a> now and add your OpenID under "My account".', array('@login' => url('user/login'))), 'warning');
       // Append form validation errors below the above warning.
       foreach ($messages['error'] as $message) {
-        drupal_set_message( $message, 'error');
+        drupal_set_message($message, 'error');
       }
     }
 
@@ -650,6 +656,80 @@ function openid_authentication($response) {
   drupal_goto();
 }
 
+/**
+ * Provides transition for accounts with possibly invalid OpenID identifiers in authmap.
+ *
+ * This function provides a safe and less obtrusive procedure for users who
+ * cannot login with their OpenID identifiers. OpenID identifiers in the
+ * authmap could be incomplete due to invalid OpenID implementation in previous
+ * versions of Drupal (e.g. fragment part of the identifier could be missing).
+ * For more information read http://drupal.org/node/1120290.
+ *
+ * @param string $identity
+ *   The user's claimed OpenID identifier.
+ *
+ * @return
+ *   A fully-loaded user object if the user is found or FALSE if not found.
+ */
+function _openid_invalid_openid_transition($identity, $response) {
+  $account = FALSE;
+  $fallback_account = NULL;
+  $fallback_identity = $identity;
+
+  // Step 1: Try to strip the fragment if it is present.
+  if (strpos($fallback_identity, '#') !== FALSE) {
+    $fallback_identity = preg_replace('/#[^?]*/', '', $fallback_identity);
+    $fallback_account = user_external_load($fallback_identity);
+  }
+
+  // Step 2: Try to replace https with http. OpenID providers often redirects
+  // from http to https, but Drupal didn't follow these redirects.
+  if (!$fallback_account && strpos($fallback_identity, 'https://') !== FALSE) {
+    $fallback_identity = str_replace('https://', 'http://', $fallback_identity);
+    $fallback_account = user_external_load($fallback_identity);
+  }
+
+  // Step 3: Try to use original identifier.
+  if (!$fallback_account && isset($_SESSION['openid']['user_login_values']['openid_identifier'])) {
+    $fallback_identity = openid_normalize($_SESSION['openid']['user_login_values']['openid_identifier']);
+    $fallback_account = user_external_load($fallback_identity);
+  }
+
+  if (isset($fallback_account->uid)) {
+    // Try to extract e-mail address from Simple Registration (SREG) or
+    // Attribute Exchanges (AX) keys.
+    $email = '';
+    $sreg_values = openid_extract_namespace($response, OPENID_NS_SREG, 'sreg');
+    $ax_values = openid_extract_namespace($response, OPENID_NS_AX, 'ax');
+    if (!empty($sreg_values['email']) && valid_email_address($sreg_values['email'])) {
+      $email = $sreg_values['email'];
+    }
+    elseif ($ax_mail_values = openid_extract_ax_values($ax_values, array('http://axschema.org/contact/email', 'http://schema.openid.net/contact/email'))) {
+      $email = current($ax_mail_values);
+    }
+
+    // If this e-mail address is the same as the e-mail address found in user
+    // account, login the user and update the claimed identifier.
+    if ($email && ($email == $fallback_account->mail || $email == $fallback_account->init)) {
+      $query = db_update('authmap')
+        ->fields(array('authname' => $identity))
+        ->condition('authname', $fallback_identity)
+        ->condition('uid', $fallback_account->uid)
+        ->condition('module', 'openid')
+        ->execute();
+      drupal_set_message(t('Successfully updated %invalid_identity with %identity.', array('%invalid_identity' => $fallback_identity, '%identity' => $identity)));
+      // Set the account to the found one.
+      $account =& $fallback_account;
+    }
+    else {
+      drupal_set_message(t('There is already an existing account associated with the OpenID identifier that you have provided. However, due to the bug in the previous version of the authentication system, we can\'t be sure that this account belongs to you. If you are new on this site, please continue registering the new user account. If you already have a registered account on this site associated with the provided OpenID identifier, please try to <a href="@url_password">reset the password</a> or contact the site administrator.', array('@url_password' => 'user/password')), 'warning');
+    }
+  }
+
+  return $account;
+}
+
+
 function openid_association_request($public) {
   module_load_include('inc', 'openid');
 
diff --git a/modules/openid/openid.test b/modules/openid/openid.test
index 202a835..aa304be 100644
--- a/modules/openid/openid.test
+++ b/modules/openid/openid.test
@@ -479,6 +479,114 @@ class OpenIDRegistrationTestCase extends OpenIDWebTestCase {
 }
 
 /**
+ * Test account registration using Simple Registration and Attribute Exchange.
+ */
+class OpenIDInvalidIdentifierTransitionTestCase extends OpenIDFunctionalTestCase  {
+  public static function getInfo() {
+    return array(
+      'name' => 'OpenID account update',
+      'description' => 'Tries to correct OpenID identifiers attached to accounts if their identifiers were stripped.',
+      'group' => 'OpenID',
+    );
+  }
+
+  function setUp() {
+    parent::setUp('openid', 'openid_test');
+    variable_set('user_register', USER_REGISTER_VISITORS);
+  }
+
+  /**
+   * Test OpenID transition with e-mail mismatch.
+   */
+  function testStrippedFragmentAccountEmailMismatch() {
+    $this->drupalLogin($this->web_user);
+
+    // Use a User-supplied Identity that is the URL of an XRDS document.
+    $identity = url('openid-test/yadis/xrds', array('absolute' => TRUE, 'fragment' => $this->randomName()));
+    $identity_stripped = preg_replace('/#[^?]*/', '', $identity);
+
+    $this->addIdentity($identity_stripped);
+
+    $this->drupalLogout();
+
+    // Test logging in via the login block on the front page.
+    $this->submitLoginForm($identity);
+    $this->assertLink(t('Log out'), 0, t('User was logged in.'));
+
+    $this->drupalLogout();
+
+    // Test logging in via the user/login page, provider will respond with full
+    // identifier (including fragment) but with different email, so we can't
+    // provide auto-update.
+    variable_set('openid_test_response', array(
+      'openid.claimed_id' => $identity,
+      'openid.sreg.nickname' => $this->web_user->name,
+      'openid.sreg.email' => 'invalid-' . $this->web_user->mail));
+    $edit = array('openid_identifier' => $identity_stripped);
+    $this->drupalPost('user/login', $edit, t('Log in'));
+
+    // Check we are on the OpenID redirect form.
+    $this->assertTitle(t('OpenID redirect'), t('OpenID redirect page was displayed.'));
+
+    // Submit form to the OpenID Provider Endpoint.
+    $this->drupalPost(NULL, array(), t('Send'));
+
+    // Verify user was redirected away from user/login to an accessible page.
+    $this->assertResponse(200);
+
+    // Verify the message.
+    $this->assertRaw(t('There is already an existing account associated with the OpenID identifier that you have provided.'), t('Message that OpenID identifier must be updated manually was displayed.'));
+
+    variable_set('openid_test_response', array());
+  }
+
+  /**
+   * Test OpenID auto transition with e-mail.
+   */
+  function testStrippedFragmentAccountAutoUpdateSreg() {
+    $this->drupalLogin($this->web_user);
+
+    // Use a User-supplied Identity that is the URL of an XRDS document.
+    $identity = url('openid-test/yadis/xrds', array('absolute' => TRUE, 'fragment' => $this->randomName()));
+    $identity_stripped = preg_replace('/#[^?]*/', '', $identity);
+
+    $this->addIdentity($identity_stripped);
+
+    $this->drupalLogout();
+
+    // Test logging in via the login block on the front page.
+    $this->submitLoginForm($identity);
+    $this->assertLink(t('Log out'), 0, t('User was logged in.'));
+
+    $this->drupalLogout();
+
+    // Test logging in via the user/login page, provider will respond with full
+    // identifier (including fragment) but with different email, so we can't
+    // provide auto-update.
+    variable_set('openid_test_response', array(
+      'openid.claimed_id' => $identity,
+      'openid.sreg.nickname' => $this->web_user->name,
+      'openid.sreg.email' => $this->web_user->mail));
+    $edit = array('openid_identifier' => $identity_stripped);
+    $this->drupalPost('user/login', $edit, t('Log in'));
+
+    // Check we are on the OpenID redirect form.
+    $this->assertTitle(t('OpenID redirect'), t('OpenID redirect page was displayed.'));
+
+    // Submit form to the OpenID Provider Endpoint.
+    $this->drupalPost(NULL, array(), t('Send'));
+
+    // Verify user was redirected away from user/login to an accessible page.
+    $this->assertResponse(200);
+
+    // Verify the message.
+    $this->assertRaw(t('Successfully updated %identity_stripped with %identity.', array('%identity_stripped' => $identity_stripped, '%identity' => $identity)), t('Message that OpenID identifier was updated automatically was displayed.'));
+
+    variable_set('openid_test_response', array());
+  }
+}
+
+/**
  * Test internal helper functions.
  */
 class OpenIDUnitTest extends DrupalWebTestCase {
diff --git a/modules/openid/tests/openid_test.module b/modules/openid/tests/openid_test.module
index bad1184..b5c023e 100644
--- a/modules/openid/tests/openid_test.module
+++ b/modules/openid/tests/openid_test.module
@@ -60,6 +60,12 @@ function openid_test_menu() {
     'access callback' => TRUE,
     'type' => MENU_CALLBACK,
   );
+  $items['openid-test/redirect'] = array(
+    'title' => 'OpenID Redirect',
+    'page callback' => 'openid_test_redirect',
+    'access callback' => TRUE,
+    'type' => MENU_CALLBACK,
+  );
   return $items;
 }
 
@@ -213,6 +219,16 @@ function openid_test_endpoint() {
 }
 
 /**
+ * Menu callback; regular HTML page with OpenID 2.0 <link> element.
+ */
+function openid_test_redirect() {
+  $url = variable_get('openid_test_redirect_url', '');
+  $http_response_code = variable_get('openid_test_redirect_http_reponse_code', 301);
+  header('Location: ' . $url, TRUE, $http_response_code);
+  exit();
+}
+
+/**
  * OpenID endpoint; handle "associate" requests (see OpenID Authentication 2.0,
  * section 8).
  *