diff --git a/typo3/sysext/core/Classes/Cache/Frontend/PhpFrontend.php b/typo3/sysext/core/Classes/Cache/Frontend/PhpFrontend.php
index 84d1a1cf9a0e..8c2cd7e6780d 100644
--- a/typo3/sysext/core/Classes/Cache/Frontend/PhpFrontend.php
+++ b/typo3/sysext/core/Classes/Cache/Frontend/PhpFrontend.php
@@ -23,7 +23,7 @@
  * This file is a backport from FLOW3
  * @api
  */
-class PhpFrontend extends StringFrontend
+class PhpFrontend extends AbstractFrontend
 {
     /**
      * Constructs the cache
@@ -64,6 +64,45 @@ public function set($entryIdentifier, $sourceCode, array $tags = [], $lifetime =
         $this->backend->set($entryIdentifier, $sourceCode, $tags, $lifetime);
     }
 
+    /**
+     * Finds and returns a variable value from the cache.
+     *
+     * @param string $entryIdentifier Identifier of the cache entry to fetch
+     * @return string The value
+     * @throws \InvalidArgumentException if the cache identifier is not valid
+     * @api
+     */
+    public function get($entryIdentifier)
+    {
+        if (!$this->isValidEntryIdentifier($entryIdentifier)) {
+            throw new \InvalidArgumentException('"' . $entryIdentifier . '" is not a valid cache entry identifier.', 1233057753);
+        }
+        return $this->backend->get($entryIdentifier);
+    }
+
+    /**
+     * Finds and returns all cache entries which are tagged by the specified tag.
+     *
+     * @param string $tag The tag to search for
+     * @return array An array with the content of all matching entries. An empty array if no entries matched
+     * @throws \InvalidArgumentException if the tag is not valid
+     * @api
+     * @deprecated since TYPO3 v9, Avoid using this method since it is not compliant to PSR-6
+     */
+    public function getByTag($tag)
+    {
+        trigger_error('This method will be removed in TYPO3 v10. Avoid using this method since it is not compliant to PSR-6.', E_USER_DEPRECATED);
+        if (!$this->isValidTag($tag)) {
+            throw new \InvalidArgumentException('"' . $tag . '" is not a valid tag for a cache entry.', 1233057773);
+        }
+        $entries = [];
+        $identifiers = $this->backend->findIdentifiersByTag($tag);
+        foreach ($identifiers as $identifier) {
+            $entries[] = $this->backend->get($identifier);
+        }
+        return $entries;
+    }
+
     /**
      * Loads PHP code from the cache and require_onces it right away.
      *
diff --git a/typo3/sysext/core/Classes/Cache/Frontend/StringFrontend.php b/typo3/sysext/core/Classes/Cache/Frontend/StringFrontend.php
index 3fb376a36ff9..8d6803a11a59 100644
--- a/typo3/sysext/core/Classes/Cache/Frontend/StringFrontend.php
+++ b/typo3/sysext/core/Classes/Cache/Frontend/StringFrontend.php
@@ -14,6 +14,7 @@
  * The TYPO3 project - inspiring people to share!
  */
 
+use TYPO3\CMS\Core\Cache\Backend\BackendInterface;
 use TYPO3\CMS\Core\Cache\Exception\InvalidDataException;
 
 /**
@@ -21,9 +22,27 @@
  *
  * This file is a backport from FLOW3
  * @api
+ * @deprecated since TYPO3 v9, will be removed in TYPO3 v10 - use VariableFrontend instead.
  */
 class StringFrontend extends AbstractFrontend
 {
+    /**
+     * @param string $identifier
+     * @param BackendInterface $backend
+     */
+    public function __construct($identifier, BackendInterface $backend)
+    {
+        trigger_error(
+            sprintf(
+                'Usage of class %s will be removed in TYPO3 v10.0, use %s instead',
+                static::class,
+                VariableFrontend::class
+            ),
+            E_USER_DEPRECATED
+        );
+        parent::__construct($identifier, $backend);
+    }
+
     /**
      * Saves the value of a PHP variable in the cache.
      *
diff --git a/typo3/sysext/core/Documentation/Changelog/master/Deprecation-81434-StringCacheFrontendDeprecated.rst b/typo3/sysext/core/Documentation/Changelog/master/Deprecation-81434-StringCacheFrontendDeprecated.rst
new file mode 100644
index 000000000000..d59abeb089d6
--- /dev/null
+++ b/typo3/sysext/core/Documentation/Changelog/master/Deprecation-81434-StringCacheFrontendDeprecated.rst
@@ -0,0 +1,32 @@
+.. include:: ../../Includes.txt
+
+======================================================
+Deprecation: #81434 - String Cache Frontend Deprecated
+======================================================
+
+See :issue:`81434`
+
+Description
+===========
+
+The ``StringFrontend`` cache frontend has been deprecated in favor of VariableFrontend.
+
+
+Impact
+======
+
+The ``TYPO3\CMS\Core\Cache\Frontend\StringFrontend`` class is deprecated.
+
+
+Affected Installations
+======================
+
+Any TYPO3 installation which defines any custom cache using ``StringFrontend``.
+
+
+Migration
+=========
+
+Replace ``TYPO3\CMS\Core\Cache\Frontend\StringFrontend`` occurrences in cache configurations with ``TYPO3\CMS\Core\Cache\Frontend\VariableFrontend``.
+
+.. index:: PHP-API, NotScanned
\ No newline at end of file
diff --git a/typo3/sysext/core/Tests/Unit/Cache/Frontend/AbstractFrontendTest.php b/typo3/sysext/core/Tests/Unit/Cache/Frontend/AbstractFrontendTest.php
index 7a6839d85567..1ec7fae0e281 100644
--- a/typo3/sysext/core/Tests/Unit/Cache/Frontend/AbstractFrontendTest.php
+++ b/typo3/sysext/core/Tests/Unit/Cache/Frontend/AbstractFrontendTest.php
@@ -31,7 +31,7 @@ public function theConstructorAcceptsValidIdentifiers()
             ->disableOriginalConstructor()
             ->getMock();
         foreach (['x', 'someValue', '123fivesixseveneight', 'some&', 'ab_cd%', rawurlencode('resource://some/äöü$&% sadf'), str_repeat('x', 250)] as $identifier) {
-            $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+            $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
                 ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag', 'flush', 'flushByTag', 'collectGarbage'])
                 ->setConstructorArgs([$identifier, $mockBackend])
                 ->getMock();
@@ -49,7 +49,7 @@ public function theConstructorRejectsInvalidIdentifiers()
             ->getMock();
         foreach (['', 'abc def', 'foo!', 'bar:', 'some/', 'bla*', 'one+', 'äöü', str_repeat('x', 251), 'x$', '\\a', 'b#'] as $identifier) {
             try {
-                $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+                $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
                     ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag', 'flush', 'flushByTag', 'collectGarbage'])
                     ->setConstructorArgs([$identifier, $mockBackend])
                     ->getMock();
@@ -70,7 +70,7 @@ public function flushCallsBackend()
             ->disableOriginalConstructor()
             ->getMock();
         $backend->expects($this->once())->method('flush');
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
@@ -88,7 +88,7 @@ public function flushByTagRejectsInvalidTags()
         $identifier = 'someCacheIdentifier';
         $backend = $this->createMock(\TYPO3\CMS\Core\Cache\Backend\TaggableBackendInterface::class);
         $backend->expects($this->never())->method('flushByTag');
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
@@ -107,7 +107,7 @@ public function flushByTagCallsBackendIfItIsATaggableBackend()
             ->disableOriginalConstructor()
             ->getMock();
         $backend->expects($this->once())->method('flushByTag')->with($tag);
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
@@ -126,7 +126,7 @@ public function flushByTagsCallsBackendIfItIsATaggableBackend()
             ->disableOriginalConstructor()
             ->getMock();
         $backend->expects($this->once())->method('flushByTags')->with([$tag]);
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
@@ -144,7 +144,7 @@ public function collectGarbageCallsBackend()
             ->disableOriginalConstructor()
             ->getMock();
         $backend->expects($this->once())->method('collectGarbage');
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
@@ -158,7 +158,7 @@ public function invalidEntryIdentifiersAreRecognizedAsInvalid()
     {
         $identifier = 'someCacheIdentifier';
         $backend = $this->createMock(\TYPO3\CMS\Core\Cache\Backend\AbstractBackend::class);
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
@@ -174,7 +174,7 @@ public function validEntryIdentifiersAreRecognizedAsValid()
     {
         $identifier = 'someCacheIdentifier';
         $backend = $this->createMock(\TYPO3\CMS\Core\Cache\Backend\AbstractBackend::class);
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
@@ -190,7 +190,7 @@ public function invalidTagsAreRecognizedAsInvalid()
     {
         $identifier = 'someCacheIdentifier';
         $backend = $this->createMock(\TYPO3\CMS\Core\Cache\Backend\AbstractBackend::class);
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
@@ -206,7 +206,7 @@ public function validTagsAreRecognizedAsValid()
     {
         $identifier = 'someCacheIdentifier';
         $backend = $this->createMock(\TYPO3\CMS\Core\Cache\Backend\AbstractBackend::class);
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['__construct', 'get', 'set', 'has', 'remove', 'getByTag'])
             ->setConstructorArgs([$identifier, $backend])
             ->getMock();
diff --git a/typo3/sysext/core/Tests/Unit/Cache/Frontend/PhpFrontendTest.php b/typo3/sysext/core/Tests/Unit/Cache/Frontend/PhpFrontendTest.php
index f06b688cf9ed..73f45868b549 100644
--- a/typo3/sysext/core/Tests/Unit/Cache/Frontend/PhpFrontendTest.php
+++ b/typo3/sysext/core/Tests/Unit/Cache/Frontend/PhpFrontendTest.php
@@ -28,9 +28,9 @@ class PhpFrontendTest extends \TYPO3\TestingFramework\Core\Unit\UnitTestCase
     public function setChecksIfTheIdentifierIsValid()
     {
         $this->expectException(\InvalidArgumentException::class);
-        $this->expectExceptionCode(1233057566);
+        $this->expectExceptionCode(1264023823);
 
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\PhpFrontend::class)
             ->setMethods(['isValidEntryIdentifier'])
             ->disableOriginalConstructor()
             ->getMock();
diff --git a/typo3/sysext/core/Tests/Unit/Cache/Frontend/VariableFrontendTest.php b/typo3/sysext/core/Tests/Unit/Cache/Frontend/VariableFrontendTest.php
index aa5396976568..83d2e618f1b7 100644
--- a/typo3/sysext/core/Tests/Unit/Cache/Frontend/VariableFrontendTest.php
+++ b/typo3/sysext/core/Tests/Unit/Cache/Frontend/VariableFrontendTest.php
@@ -14,12 +14,12 @@
  * The TYPO3 project - inspiring people to share!
  */
 
+use TYPO3\TestingFramework\Core\Unit\UnitTestCase;
+
 /**
- * Testcase for the variable cache frontend
- *
- * This file is a backport from FLOW3
+ * Test case
  */
-class VariableFrontendTest extends \TYPO3\TestingFramework\Core\Unit\UnitTestCase
+class VariableFrontendTest extends UnitTestCase
 {
     /**
      * @test
@@ -27,9 +27,9 @@ class VariableFrontendTest extends \TYPO3\TestingFramework\Core\Unit\UnitTestCas
     public function setChecksIfTheIdentifierIsValid()
     {
         $this->expectException(\InvalidArgumentException::class);
-        $this->expectExceptionCode(1233057566);
+        $this->expectExceptionCode(1233058264);
 
-        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cache = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['isValidEntryIdentifier'])
             ->disableOriginalConstructor()
             ->getMock();
diff --git a/typo3/sysext/core/Tests/Unit/Localization/LocalizationFactoryTest.php b/typo3/sysext/core/Tests/Unit/Localization/LocalizationFactoryTest.php
index 18f24472b7f5..f0edd747230e 100644
--- a/typo3/sysext/core/Tests/Unit/Localization/LocalizationFactoryTest.php
+++ b/typo3/sysext/core/Tests/Unit/Localization/LocalizationFactoryTest.php
@@ -71,7 +71,7 @@ public function getParsedDataCallsLocalizationOverrideIfFileNotFoundExceptionIsT
         $languageStore = $this->getMockBuilder(\TYPO3\CMS\Core\Localization\LanguageStore::class)
             ->setMethods(['hasData', 'setConfiguration', 'getData', 'setData'])
             ->getMock();
-        $cacheInstance = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class)
+        $cacheInstance = $this->getMockBuilder(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class)
             ->setMethods(['get', 'set'])
             ->disableOriginalConstructor()
             ->getMock();
diff --git a/typo3/sysext/core/Tests/Unit/Cache/Frontend/StringFrontendTest.php b/typo3/sysext/core/Tests/UnitDeprecated/Cache/Frontend/StringFrontendTest.php
similarity index 98%
rename from typo3/sysext/core/Tests/Unit/Cache/Frontend/StringFrontendTest.php
rename to typo3/sysext/core/Tests/UnitDeprecated/Cache/Frontend/StringFrontendTest.php
index 44101410cbec..7cd7b2113dee 100644
--- a/typo3/sysext/core/Tests/Unit/Cache/Frontend/StringFrontendTest.php
+++ b/typo3/sysext/core/Tests/UnitDeprecated/Cache/Frontend/StringFrontendTest.php
@@ -1,5 +1,5 @@
 <?php
-namespace TYPO3\CMS\Core\Tests\Unit\Cache\Frontend;
+namespace TYPO3\CMS\Core\Tests\UnitDeprecated\Cache\Frontend;
 
 /*
  * This file is part of the TYPO3 CMS project.
diff --git a/typo3/sysext/scheduler/Tests/Unit/Task/CachingFrameworkGarbageCollectionTest.php b/typo3/sysext/scheduler/Tests/Unit/Task/CachingFrameworkGarbageCollectionTest.php
index 790b3323d30e..b0ad4b40e7c1 100644
--- a/typo3/sysext/scheduler/Tests/Unit/Task/CachingFrameworkGarbageCollectionTest.php
+++ b/typo3/sysext/scheduler/Tests/Unit/Task/CachingFrameworkGarbageCollectionTest.php
@@ -48,7 +48,7 @@ protected function tearDown()
      */
     public function executeCallsCollectGarbageOfConfiguredBackend()
     {
-        $cache = $this->createMock(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class);
+        $cache = $this->createMock(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class);
         $cache->expects($this->any())->method('getIdentifier')->will($this->returnValue('cache'));
         $cache->expects($this->atLeastOnce())->method('collectGarbage');
         $mockCacheManager = new \TYPO3\CMS\Core\Cache\CacheManager();
@@ -56,7 +56,7 @@ public function executeCallsCollectGarbageOfConfiguredBackend()
         GeneralUtility::setSingletonInstance(\TYPO3\CMS\Core\Cache\CacheManager::class, $mockCacheManager);
         $GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations'] = [
             'cache' => [
-                'frontend' => \TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class,
+                'frontend' => \TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class,
                 'backend' => \TYPO3\CMS\Core\Cache\Backend\AbstractBackend::class,
             ]
         ];
@@ -74,7 +74,7 @@ public function executeCallsCollectGarbageOfConfiguredBackend()
      */
     public function executeDoesNotCallCollectGarbageOfNotConfiguredBackend()
     {
-        $cache = $this->createMock(\TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class);
+        $cache = $this->createMock(\TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class);
         $cache->expects($this->any())->method('getIdentifier')->will($this->returnValue('cache'));
         $cache->expects($this->never())->method('collectGarbage');
         $mockCacheManager = new \TYPO3\CMS\Core\Cache\CacheManager();
@@ -82,7 +82,7 @@ public function executeDoesNotCallCollectGarbageOfNotConfiguredBackend()
         GeneralUtility::setSingletonInstance(\TYPO3\CMS\Core\Cache\CacheManager::class, $mockCacheManager);
         $GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations'] = [
             'cache' => [
-                'frontend' => \TYPO3\CMS\Core\Cache\Frontend\StringFrontend::class,
+                'frontend' => \TYPO3\CMS\Core\Cache\Frontend\VariableFrontend::class,
                 'backend' => \TYPO3\CMS\Core\Cache\Backend\AbstractBackend::class,
             ]
         ];