diff --git a/src/Exception/RedisRuntimeException.php b/src/Exception/RedisRuntimeException.php
index d2fe05a..b369549 100644
--- a/src/Exception/RedisRuntimeException.php
+++ b/src/Exception/RedisRuntimeException.php
@@ -13,6 +13,8 @@
 
 final class RedisRuntimeException extends LaminasCacheRuntimeException
 {
+    private const INTERNAL_REDIS_ERROR = 'Something went wrong while interacting with redis cluster.';
+
     public static function fromClusterException(RedisClusterException $exception, RedisCluster $redis): self
     {
         $message = $redis->getLastError() ?? $exception->getMessage();
@@ -39,4 +41,15 @@ public static function fromRedisException(RedisException $exception, Redis $redi
 
         return new self($message, $exception->getCode(), $exception);
     }
+
+    public static function fromInternalRedisError(RedisCluster|Redis $redis): self
+    {
+        try {
+            $message = $redis->getLastError() ?? self::INTERNAL_REDIS_ERROR;
+        } catch (RedisException) {
+            $message = self::INTERNAL_REDIS_ERROR;
+        }
+
+        return new self($message);
+    }
 }
diff --git a/src/RedisCluster.php b/src/RedisCluster.php
index 7847cb6..4ed5584 100644
--- a/src/RedisCluster.php
+++ b/src/RedisCluster.php
@@ -19,8 +19,11 @@
 
 use function array_key_exists;
 use function array_values;
+use function assert;
 use function count;
 use function in_array;
+use function is_array;
+use function is_int;
 use function sprintf;
 use function version_compare;
 
@@ -192,14 +195,23 @@ protected function internalGetItems(array &$normalizedKeys): array
         $redis = $this->getRedisResource();
 
         try {
-            /** @var array<int,mixed> $resultsByIndex */
             $resultsByIndex = $redis->mget($namespacedKeys);
         } catch (RedisClusterException $exception) {
             throw $this->clusterException($exception, $redis);
         }
 
+        /**
+         * @link https://github.com/phpredis/phpredis/blob/35a7cc094c6c264aa37738b074c4c54c4ca73b87/redis_cluster.stub.php#L621
+         *
+         * @psalm-suppress TypeDoesNotContainType RedisCluster#mget can return `false` on error
+         */
+        if (! is_array($resultsByIndex)) {
+            throw RedisRuntimeException::fromInternalRedisError($redis);
+        }
+
         $result = [];
         foreach ($resultsByIndex as $keyIndex => $value) {
+            assert(is_int($keyIndex));
             $normalizedKey = $normalizedKeys[$keyIndex];
             $namespacedKey = $namespacedKeys[$keyIndex];
             if ($value === false && ! $this->isFalseReturnValuePersisted($redis, $namespacedKey)) {