diff --git a/cache/classes/dummystore.php b/cache/classes/dummystore.php
index c11e197cd0c..bcc9ca1e72f 100644
--- a/cache/classes/dummystore.php
+++ b/cache/classes/dummystore.php
@@ -258,7 +258,9 @@ class cachestore_dummy extends cache_store {
      */
     public static function initialise_test_instance(cache_definition $definition) {
         $cache = new cachestore_dummy('Dummy store test');
-        $cache->initialise($definition);
+        if ($cache->is_ready()) {
+            $cache->initialise($definition);
+        }
         return $cache;
     }
 
diff --git a/cache/stores/apcu/lib.php b/cache/stores/apcu/lib.php
index cbb20db9110..077a5d7a3ff 100644
--- a/cache/stores/apcu/lib.php
+++ b/cache/stores/apcu/lib.php
@@ -155,15 +155,6 @@ class cachestore_apcu extends cache_store implements cache_is_key_aware, cache_i
         return ($this->definition !== null);
     }
 
-    /**
-     * Returns true if this cache store instance is ready to use.
-     * @return bool
-     */
-    public function is_ready() {
-        // No set up is actually required, providing apc is installed and enabled.
-        return true;
-    }
-
     /**
      * Prepares the given key for use.
      *
@@ -325,6 +316,7 @@ class cachestore_apcu extends cache_store implements cache_is_key_aware, cache_i
         }
         $name = 'APCu test';
         $cache = new cachestore_apcu($name);
+        // No need to check if is_ready() as this has already being done by requirement check.
         $cache->initialise($definition);
         return $cache;
     }
diff --git a/cache/stores/file/lib.php b/cache/stores/file/lib.php
index 91a0839b3d5..dd5e05825e4 100644
--- a/cache/stores/file/lib.php
+++ b/cache/stores/file/lib.php
@@ -673,7 +673,9 @@ class cachestore_file extends cache_store implements cache_is_key_aware, cache_i
         $name = 'File test';
         $path = make_cache_directory('cachestore_file_test');
         $cache = new cachestore_file($name, array('path' => $path));
-        $cache->initialise($definition);
+        if ($cache->is_ready()) {
+            $cache->initialise($definition);
+        }
         return $cache;
     }
 
diff --git a/cache/stores/memcache/lib.php b/cache/stores/memcache/lib.php
index 6f89d1ace95..60ee49b3b99 100644
--- a/cache/stores/memcache/lib.php
+++ b/cache/stores/memcache/lib.php
@@ -576,7 +576,9 @@ class cachestore_memcache extends cache_store implements cache_is_configurable {
         }
 
         $store = new cachestore_memcache('Test memcache', $configuration);
-        $store->initialise($definition);
+        if ($store->is_ready()) {
+            $store->initialise($definition);
+        }
 
         return $store;
     }
diff --git a/cache/stores/memcache/tests/memcache_test.php b/cache/stores/memcache/tests/memcache_test.php
index 18f486a77ba..f5d4f087b7f 100644
--- a/cache/stores/memcache/tests/memcache_test.php
+++ b/cache/stores/memcache/tests/memcache_test.php
@@ -58,12 +58,12 @@ class cachestore_memcache_test extends cachestore_tests {
 
         $definition = cache_definition::load_adhoc(cache_store::MODE_APPLICATION, 'cachestore_memcache', 'phpunit_test');
         $instance = new cachestore_memcache('Memcache Test', cachestore_memcache::unit_test_configuration());
-        $instance->initialise($definition);
 
         if (!$instance->is_ready()) {
             // Something prevented memcache store to be inited (extension, TEST_CACHESTORE_MEMCACHE_TESTSERVERS...).
             $this->markTestSkipped();
         }
+        $instance->initialise($definition);
 
         $keys = array(
             // Alphanumeric.
diff --git a/cache/stores/memcached/lib.php b/cache/stores/memcached/lib.php
index 0c7be7bb9ca..56df93771b9 100644
--- a/cache/stores/memcached/lib.php
+++ b/cache/stores/memcached/lib.php
@@ -733,7 +733,10 @@ class cachestore_memcached extends cache_store implements cache_is_configurable
         }
 
         $store = new cachestore_memcached($name, $configuration);
-        $store->initialise($definition);
+        // If store is ready then only initialise.
+        if ($store->is_ready()) {
+            $store->initialise($definition);
+        }
 
         return $store;
     }
diff --git a/cache/stores/memcached/tests/memcached_test.php b/cache/stores/memcached/tests/memcached_test.php
index 87517c02b9c..bef5cbe2704 100644
--- a/cache/stores/memcached/tests/memcached_test.php
+++ b/cache/stores/memcached/tests/memcached_test.php
@@ -62,12 +62,12 @@ class cachestore_memcached_test extends cachestore_tests {
 
         $definition = cache_definition::load_adhoc(cache_store::MODE_APPLICATION, 'cachestore_memcached', 'phpunit_test');
         $instance = new cachestore_memcached('Memcached Test', cachestore_memcached::unit_test_configuration());
-        $instance->initialise($definition);
 
         if (!$instance->is_ready()) {
             // Something prevented memcached store to be inited (extension, TEST_CACHESTORE_MEMCACHED_TESTSERVERS...).
             $this->markTestSkipped();
         }
+        $instance->initialise($definition);
 
         $keys = array(
             // Alphanumeric.
@@ -183,7 +183,7 @@ class cachestore_memcached_test extends cachestore_tests {
             set_config('testname', $testserver, 'cachestore_memcached');
             set_config('testservers', $testserver, 'cachestore_memcached');
             $checkinstance = cachestore_memcached::initialise_test_instance($definition);
-            if (!$checkinstance) {
+            if (!$checkinstance->is_ready()) {
                 $this->markTestSkipped();
             }
             $checkinstances[] = $checkinstance;
diff --git a/cache/stores/mongodb/tests/mongodb_test.php b/cache/stores/mongodb/tests/mongodb_test.php
index edb7f76ad20..8e97822f2fa 100644
--- a/cache/stores/mongodb/tests/mongodb_test.php
+++ b/cache/stores/mongodb/tests/mongodb_test.php
@@ -57,11 +57,11 @@ class cachestore_mongodb_test extends cachestore_tests {
         // This generates a definition that has a hash starting with a number. MDL-46208.
         $definition = cache_definition::load_adhoc(cache_store::MODE_APPLICATION, 'cachestore_mongodb', 'abc');
         $instance = new cachestore_mongodb('MongoDB_Test', cachestore_mongodb::unit_test_configuration());
-        $instance->initialise($definition);
 
         if (!$instance->is_ready()) {
             $this->markTestSkipped();
         }
+        $instance->initialise($definition);
 
         $this->assertTrue($instance->set(1, 'alpha'));
         $this->assertTrue($instance->set(2, 'beta'));
diff --git a/cache/tests/fixtures/stores.php b/cache/tests/fixtures/stores.php
index 7048a7d120e..c1046b76813 100644
--- a/cache/tests/fixtures/stores.php
+++ b/cache/tests/fixtures/stores.php
@@ -63,33 +63,33 @@ abstract class cachestore_tests extends advanced_testcase {
         if ($modes & cache_store::MODE_APPLICATION) {
             $definition = cache_definition::load_adhoc(cache_store::MODE_APPLICATION, $class, 'phpunit_test');
             $instance = new $class($class.'_test', $class::unit_test_configuration());
-            $instance->initialise($definition);
 
             if (!$instance->is_ready()) {
                 $this->markTestSkipped('Could not test '.$class.'. No test instance configured for application caches.');
             } else {
+                $instance->initialise($definition);
                 $this->run_tests($instance);
             }
         }
         if ($modes & cache_store::MODE_SESSION) {
             $definition = cache_definition::load_adhoc(cache_store::MODE_SESSION, $class, 'phpunit_test');
             $instance = new $class($class.'_test', $class::unit_test_configuration());
-            $instance->initialise($definition);
 
             if (!$instance->is_ready()) {
                 $this->markTestSkipped('Could not test '.$class.'. No test instance configured for session caches.');
             } else {
+                $instance->initialise($definition);
                 $this->run_tests($instance);
             }
         }
         if ($modes & cache_store::MODE_REQUEST) {
             $definition = cache_definition::load_adhoc(cache_store::MODE_REQUEST, $class, 'phpunit_test');
             $instance = new $class($class.'_test', $class::unit_test_configuration());
-            $instance->initialise($definition);
 
             if (!$instance->is_ready()) {
                 $this->markTestSkipped('Could not test '.$class.'. No test instance configured for request caches.');
             } else {
+                $instance->initialise($definition);
                 $this->run_tests($instance);
             }
         }