diff --git a/lib/Controller/SAMLController.php b/lib/Controller/SAMLController.php
index 22cbcab51..5946f80d7 100644
--- a/lib/Controller/SAMLController.php
+++ b/lib/Controller/SAMLController.php
@@ -119,6 +119,8 @@ private function autoprovisionIfPossible(array $auth) {
 				throw new \InvalidArgumentException('No valid uid given, please check your attribute mapping. Given uid: ' . $uid);
 			}
 
+			$uid = $this->userBackend->testEncodedObjectGUID($uid);
+
 			// if this server acts as a global scale master and the user is not
 			// a local admin of the server we just create the user and continue
 			// no need to update additional attributes
diff --git a/lib/UserBackend.php b/lib/UserBackend.php
index bf1539a2b..a5c3361bb 100644
--- a/lib/UserBackend.php
+++ b/lib/UserBackend.php
@@ -701,4 +701,46 @@ public function countUsers() {
 
 		return $result->fetchColumn();
 	}
+
+	/**
+	 * returns the plain text UUID if the provided $uid string is a
+	 * base64-encoded binary string representing e.g. the objectGUID. Otherwise
+	 *
+	 */
+	public function testEncodedObjectGUID(string $uid): string {
+		$candidate = base64_decode($uid, true);
+		if($candidate === false) {
+			return $uid;
+		}
+		$candidate = $this->convertObjectGUID2Str($candidate);
+		// the regex only matches the structure of the UUID, not its semantic
+		// (i.e. version or variant) simply to be future compatible
+		if(preg_match('/^[a-f0-9]{8}(-[a-f0-9]{4}){4}[a-f0-9]{8}$/i', $candidate) === 1) {
+			$uid = $candidate;
+		}
+		return $uid;
+	}
+
+	/**
+	 * @see \OCA\User_LDAP\Access::convertObjectGUID2Str
+	 */
+	protected function convertObjectGUID2Str($oguid) {
+		$hex_guid = bin2hex($oguid);
+		$hex_guid_to_guid_str = '';
+		for($k = 1; $k <= 4; ++$k) {
+			$hex_guid_to_guid_str .= substr($hex_guid, 8 - 2 * $k, 2);
+		}
+		$hex_guid_to_guid_str .= '-';
+		for($k = 1; $k <= 2; ++$k) {
+			$hex_guid_to_guid_str .= substr($hex_guid, 12 - 2 * $k, 2);
+		}
+		$hex_guid_to_guid_str .= '-';
+		for($k = 1; $k <= 2; ++$k) {
+			$hex_guid_to_guid_str .= substr($hex_guid, 16 - 2 * $k, 2);
+		}
+		$hex_guid_to_guid_str .= '-' . substr($hex_guid, 16, 4);
+		$hex_guid_to_guid_str .= '-' . substr($hex_guid, 20);
+
+		return strtoupper($hex_guid_to_guid_str);
+	}
 }
diff --git a/tests/unit/Controller/SAMLControllerTest.php b/tests/unit/Controller/SAMLControllerTest.php
index 903732b97..952e24b6e 100644
--- a/tests/unit/Controller/SAMLControllerTest.php
+++ b/tests/unit/Controller/SAMLControllerTest.php
@@ -69,6 +69,9 @@ public function setUp() {
 		$this->userSession = $this->createMock(IUserSession::class);
 		$this->samlSettings = $this->createMock(SAMLSettings::class);
 		$this->userBackend = $this->createMock(UserBackend::class);
+		$this->userBackend->expects($this->any())
+			->method('testEncodedObjectGUID')
+			->willReturnArgument(0);
 		$this->config = $this->createMock(IConfig::class);
 		$this->urlGenerator = $this->createMock(IURLGenerator::class);
 		$this->userManager = $this->createMock(IUserManager::class);
@@ -275,11 +278,11 @@ public function testLoginWithEnvVariableAndNotExistingUserWithProvisioning() {
 			->with('/')
 			->willReturn('https://nextcloud.com/absolute/');
 		$this->userBackend
-			->expects($this->at(0))
+			->expects($this->once())
 			->method('autoprovisionAllowed')
 			->willReturn(true);
 		$this->userBackend
-			->expects($this->at(1))
+			->expects($this->once())
 			->method('createUserIfNotExists')
 			->with('MyUid');
 		$this->userBackend
@@ -332,11 +335,11 @@ public function testLoginWithEnvVariableAndNotExistingUserWithMalfunctioningBack
 			->with('user_saml.SAML.notProvisioned')
 			->willReturn('https://nextcloud.com/notprovisioned/');
 		$this->userBackend
-			->expects($this->at(0))
+			->expects($this->once())
 			->method('autoprovisionAllowed')
 			->willReturn(true);
 		$this->userBackend
-			->expects($this->at(1))
+			->expects($this->once())
 			->method('createUserIfNotExists')
 			->with('MyUid');
 		$this->userBackend
diff --git a/tests/unit/UserBackendTest.php b/tests/unit/UserBackendTest.php
index e3bc722c7..28bd4353e 100644
--- a/tests/unit/UserBackendTest.php
+++ b/tests/unit/UserBackendTest.php
@@ -281,5 +281,25 @@ public function testUpdateAttributesQuotaDefaultFallback() {
 		$this->userBackend->updateAttributes('ExistingUser', ['email' => 'new@example.com', 'displayname' => 'New Displayname', 'quota' => '']);
 	}
 
+	public function objectGuidProvider() {
+		return [
+			['Joey No Conversion', 'Joey No Conversion'],
+			['no@convers.ion', 'no@convers.ion'],
+			['a0aa9ed8-6b48-1034-8ad7-8fb78330d80a', 'a0aa9ed8-6b48-1034-8ad7-8fb78330d80a'],
+			['EDE70D16-B9D5-4E9A-ABD7-614D17246E3F', 'EDE70D16-B9D5-4E9A-ABD7-614D17246E3F'],
+			['Tm8gY29udmVyc2lvbgo=', 'Tm8gY29udmVyc2lvbgo='],
+			['ASfjU2OYEd69ZgAVF4pePA==', '53E32701-9863-DE11-BD66-0015178A5E3C'],
+		];
+	}
+
+	/**
+	 * @dataProvider objectGuidProvider
+	 */
+	public function testTestEncodedObjectGUID(string $input, string $expectation) {
+		$this->getMockedBuilder(['getDisplayName', 'setDisplayName']);
+		$uid = $this->userBackend->testEncodedObjectGUID($input);
+		$this->assertSame($expectation, $uid);
+	}
+
 
 }