diff --git a/typo3/sysext/backend/Classes/Controller/File/FileController.php b/typo3/sysext/backend/Classes/Controller/File/FileController.php
index 1d4365ab49bac90be01e6258ac6e9419ccdaf8f9..152ffbdf29bac5b667422f23685e7f39599eab9d 100644
--- a/typo3/sysext/backend/Classes/Controller/File/FileController.php
+++ b/typo3/sysext/backend/Classes/Controller/File/FileController.php
@@ -137,7 +137,7 @@ class FileController {
 		// Checking referrer / executing:
 		$refInfo = parse_url(GeneralUtility::getIndpEnv('HTTP_REFERER'));
 		$httpHost = GeneralUtility::getIndpEnv('TYPO3_HOST_ONLY');
-		if ($httpHost != $refInfo['host'] && $this->vC != $this->getBackendUser()->veriCode() && !$GLOBALS['TYPO3_CONF_VARS']['SYS']['doNotCheckReferer'] && $GLOBALS['CLIENT']['BROWSER'] != 'flash') {
+		if ($httpHost !== $refInfo['host'] && $this->vC !== $this->getBackendUser()->veriCode() && !$GLOBALS['TYPO3_CONF_VARS']['SYS']['doNotCheckReferer']) {
 			$this->fileProcessor->writeLog(0, 2, 1, 'Referrer host "%s" and server host "%s" did not match!', array($refInfo['host'], $httpHost));
 		} else {
 			$this->fileProcessor->start($this->file);
diff --git a/typo3/sysext/backend/Classes/Http/AjaxRequestHandler.php b/typo3/sysext/backend/Classes/Http/AjaxRequestHandler.php
index 0b7a4b04d953c8edadad9b9438d7189e807d75f5..1b0769894f4b5a2a76a0f6183fa237e8dadb47b0 100644
--- a/typo3/sysext/backend/Classes/Http/AjaxRequestHandler.php
+++ b/typo3/sysext/backend/Classes/Http/AjaxRequestHandler.php
@@ -148,7 +148,6 @@ class AjaxRequestHandler implements RequestHandlerInterface {
 			->checkLockedBackendAndRedirectOrDie($proceedIfNoUserIsLoggedIn)
 			->checkBackendIpOrDie()
 			->checkSslBackendAndRedirectIfNeeded()
-			->checkValidBrowserOrDie()
 			->loadExtensionTables(TRUE)
 			->initializeSpriteManager()
 			->initializeBackendUser()
diff --git a/typo3/sysext/backend/Classes/Http/BackendModuleRequestHandler.php b/typo3/sysext/backend/Classes/Http/BackendModuleRequestHandler.php
index de2567134b905ec6bbd274fda73f6f29b6a942c9..0a19c3fc451c8ac308ac908c08fd8b5f26c67fac 100644
--- a/typo3/sysext/backend/Classes/Http/BackendModuleRequestHandler.php
+++ b/typo3/sysext/backend/Classes/Http/BackendModuleRequestHandler.php
@@ -105,7 +105,6 @@ class BackendModuleRequestHandler implements RequestHandlerInterface {
 		$this->bootstrap->checkLockedBackendAndRedirectOrDie()
 			->checkBackendIpOrDie()
 			->checkSslBackendAndRedirectIfNeeded()
-			->checkValidBrowserOrDie()
 			->loadExtensionTables(TRUE)
 			->initializeSpriteManager()
 			->initializeBackendUser()
diff --git a/typo3/sysext/backend/Classes/Http/RequestHandler.php b/typo3/sysext/backend/Classes/Http/RequestHandler.php
index 2860c426baf813ce9fb4910fca64a0084605cee0..066b97b36ab475a6352f2d55429e934c6987c885 100644
--- a/typo3/sysext/backend/Classes/Http/RequestHandler.php
+++ b/typo3/sysext/backend/Classes/Http/RequestHandler.php
@@ -64,7 +64,6 @@ class RequestHandler implements RequestHandlerInterface {
 			->checkLockedBackendAndRedirectOrDie()
 			->checkBackendIpOrDie()
 			->checkSslBackendAndRedirectIfNeeded()
-			->checkValidBrowserOrDie()
 			->loadExtensionTables(TRUE)
 			->initializeSpriteManager()
 			->initializeBackendUser()
diff --git a/typo3/sysext/core/Classes/Authentication/AbstractUserAuthentication.php b/typo3/sysext/core/Classes/Authentication/AbstractUserAuthentication.php
index 874d03e778bad526edf0e1b4e0fb65e4ab8ad1d3..1063406e6236348f09ee1f6db358b5b0ed776213 100644
--- a/typo3/sysext/core/Classes/Authentication/AbstractUserAuthentication.php
+++ b/typo3/sysext/core/Classes/Authentication/AbstractUserAuthentication.php
@@ -1035,22 +1035,6 @@ abstract class AbstractUserAuthentication {
 	protected function fetchUserSessionFromDB() {
 		$statement = NULL;
 		$ipLockClause = $this->ipLockClause();
-		if ($GLOBALS['CLIENT']['BROWSER'] == 'flash') {
-			// If on the flash client, the veri code is valid, then the user session is fetched
-			// from the DB without the hashLock clause
-			if (GeneralUtility::_GP('vC') == $this->veriCode()) {
-				$statement = $this->db->prepare_SELECTquery('*', $this->session_table . ',' . $this->user_table, $this->session_table . '.ses_id = :ses_id
-						AND ' . $this->session_table . '.ses_name = :ses_name
-						AND ' . $this->session_table . '.ses_userid = ' . $this->user_table . '.' . $this->userid_column . '
-						' . $ipLockClause['where'] . '
-						' . $this->user_where_clause());
-				$statement->bindValues(array(
-					':ses_id' => $this->id,
-					':ses_name' => $this->name
-				));
-				$statement->bindValues($ipLockClause['parameters']);
-			}
-		} else {
 			$statement = $this->db->prepare_SELECTquery('*', $this->session_table . ',' . $this->user_table, $this->session_table . '.ses_id = :ses_id
 					AND ' . $this->session_table . '.ses_name = :ses_name
 					AND ' . $this->session_table . '.ses_userid = ' . $this->user_table . '.' . $this->userid_column . '
@@ -1062,7 +1046,6 @@ abstract class AbstractUserAuthentication {
 				':ses_name' => $this->name
 			));
 			$statement->bindValues($ipLockClause['parameters']);
-		}
 		return $statement;
 	}
 
diff --git a/typo3/sysext/core/Classes/Core/Bootstrap.php b/typo3/sysext/core/Classes/Core/Bootstrap.php
index ced25503386517d0506f7d5c11d9c66728b9a865..b92e9f9bd8ffa4219763b33c422171f64af8ab1b 100644
--- a/typo3/sysext/core/Classes/Core/Bootstrap.php
+++ b/typo3/sysext/core/Classes/Core/Bootstrap.php
@@ -445,21 +445,6 @@ class Bootstrap {
 		return $this;
 	}
 
-	/**
-	 * Throws an exception if no browser could be identified
-	 *
-	 * @return Bootstrap
-	 * @throws \RuntimeException
-	 * @internal This is not a public API method, do not use in own extensions
-	 */
-	public function checkValidBrowserOrDie() {
-		// Checks for proper browser
-		if (empty($GLOBALS['CLIENT']['BROWSER'])) {
-			throw new \RuntimeException('Browser Error: Your browser version looks incompatible with this TYPO3 version!', 1294587023);
-		}
-		return $this;
-	}
-
 	/**
 	 * We need an early instance of the configuration manager.
 	 * Since makeInstance relies on the object configuration, we create it here with new instead.
diff --git a/typo3/sysext/core/Classes/Core/SystemEnvironmentBuilder.php b/typo3/sysext/core/Classes/Core/SystemEnvironmentBuilder.php
index dc686c3e16708d6152e400f6ac2061c7748169bd..d08ccc687fd6ce30021d75bb9bc1d77b1dac921b 100644
--- a/typo3/sysext/core/Classes/Core/SystemEnvironmentBuilder.php
+++ b/typo3/sysext/core/Classes/Core/SystemEnvironmentBuilder.php
@@ -213,8 +213,6 @@ class SystemEnvironmentBuilder {
 	static protected function initializeGlobalVariables() {
 		// Unset variable(s) in global scope (security issue #13959)
 		unset($GLOBALS['error']);
-		// Set up base information about browser/user-agent
-		$GLOBALS['CLIENT'] = GeneralUtility::clientInfo();
 		$GLOBALS['TYPO3_MISC'] = array();
 		$GLOBALS['T3_VAR'] = array();
 		$GLOBALS['T3_SERVICES'] = array();
diff --git a/typo3/sysext/core/Documentation/Changelog/master/Breaking-68150-GLOBALSCLIENT.rst b/typo3/sysext/core/Documentation/Changelog/master/Breaking-68150-GLOBALSCLIENT.rst
new file mode 100644
index 0000000000000000000000000000000000000000..c80504e071fce9343081a5f0723452f383efed29
--- /dev/null
+++ b/typo3/sysext/core/Documentation/Changelog/master/Breaking-68150-GLOBALSCLIENT.rst
@@ -0,0 +1,26 @@
+=====================================
+Breaking: #68150 - $GLOBALS['CLIENT']
+=====================================
+
+Description
+===========
+
+The initialization of the $GLOBALS['CLIENT'] variable has been dropped.
+
+
+Impact
+======
+
+Extensions that use $GLOBALS['CLIENT'] will cause a PHP notice or may not function properly any more.
+
+
+Affected Installations
+======================
+
+Installations with extensions that use $GLOBALS['CLIENT'] are affected.
+
+
+Migration
+=========
+
+Extensions can still use GeneralUtility::clientInfo() API to retrieve the same information.
\ No newline at end of file
diff --git a/typo3/sysext/core/Tests/Unit/Core/SystemEnvironmentBuilderTest.php b/typo3/sysext/core/Tests/Unit/Core/SystemEnvironmentBuilderTest.php
index 7067f1fa6fd95c8b74ba9711de4a9bfeaa7d706a..e73cdccc6dc3d420c2e398d7069076e6afd9c748 100644
--- a/typo3/sysext/core/Tests/Unit/Core/SystemEnvironmentBuilderTest.php
+++ b/typo3/sysext/core/Tests/Unit/Core/SystemEnvironmentBuilderTest.php
@@ -127,15 +127,6 @@ class SystemEnvironmentBuilderTest extends \TYPO3\CMS\Core\Tests\UnitTestCase {
 		$this->assertFalse(isset($GLOBALS['error']));
 	}
 
-	/**
-	 * @test
-	 */
-	public function initializeGlobalVariablesSetsGlobalClientArray() {
-		unset($GLOBALS['CLIENT']);
-		$this->subject->_call('initializeGlobalVariables');
-		$this->assertArrayHasKey('CLIENT', $GLOBALS);
-	}
-
 	/**
 	 * @test
 	 */