diff --git a/app/core/redis.php b/app/core/redis.php
index f848d93..8dff58e 100644
--- a/app/core/redis.php
+++ b/app/core/redis.php
@@ -1,14 +1,31 @@
 <?php
 
-function redisClient(): Redis
+function redisClient(): ?Redis
 {
     static $redis = null;
+    static $initialized = false;
+
+    if ($initialized) {
+        return $redis;
+    }
+
+    $initialized = true;
+
+    if (!class_exists('Redis')) {
+        return null;
+    }
+
     if ($redis === null) {
         $config = require __DIR__ . '/../config/config.php';
         $redis  = new Redis();
-        if (!@$redis->connect($config['redis']['host'], $config['redis']['port'])) {
-            throw new RuntimeException('Redis connection failed.');
+        try {
+            if (!@$redis->connect($config['redis']['host'], $config['redis']['port'])) {
+                $redis = null;
+            }
+        } catch (Throwable $e) {
+            $redis = null;
         }
     }
+
     return $redis;
 }
diff --git a/app/models/Paste.php b/app/models/Paste.php
index ecf512b..04729ed 100644
--- a/app/models/Paste.php
+++ b/app/models/Paste.php
@@ -21,12 +21,24 @@ class Paste
         if ($expire_time !== null) {
             $ttl = max(1, $expire_time - time());
             $redis = redisClient();
-            $redis->setex("paste:{$id}", $ttl, json_encode([
-                'encrypted_text' => $encrypted_text,
-                'iv'             => $iv,
-                'password_hash'  => $password_hash,
-            ]));
-            return true;
+            if ($redis !== null) {
+                try {
+                    $redis->setex("paste:{$id}", $ttl, json_encode([
+                        'encrypted_text' => $encrypted_text,
+                        'iv'             => $iv,
+                        'password_hash'  => $password_hash,
+                    ]));
+                    return true;
+                } catch (Throwable $e) {
+                    // Fall back to MySQL so expiring pastes still work without Redis.
+                }
+            }
+
+            $stmt = $this->pdo->prepare(
+                'INSERT INTO pastes (id, encrypted_text, iv, expire_time, password_hash)
+                 VALUES (?, ?, ?, ?, ?)'
+            );
+            return $stmt->execute([$id, $encrypted_text, $iv, $expire_time, $password_hash]);
         }
 
         $stmt = $this->pdo->prepare(
@@ -39,16 +51,21 @@ class Paste
     public function get(string $id): array|false
     {
         $redis = redisClient();
-        $raw   = $redis->get("paste:{$id}");
-
-        if ($raw !== false) {
-            $json = json_decode($raw, true);
-            return [
-                'encrypted_text' => $json['encrypted_text'],
-                'iv'             => $json['iv'],
-                'password_hash'  => $json['password_hash'],
-                'expire_time'    => time() + $redis->ttl("paste:{$id}"),
-            ];
+        if ($redis !== null) {
+            try {
+                $raw = $redis->get("paste:{$id}");
+                if ($raw !== false) {
+                    $json = json_decode($raw, true);
+                    return [
+                        'encrypted_text' => $json['encrypted_text'],
+                        'iv'             => $json['iv'],
+                        'password_hash'  => $json['password_hash'],
+                        'expire_time'    => time() + $redis->ttl("paste:{$id}"),
+                    ];
+                }
+            } catch (Throwable $e) {
+                // Ignore Redis failures and fall back to MySQL.
+            }
         }
 
         $stmt = $this->pdo->prepare('SELECT * FROM pastes WHERE id = ? LIMIT 1');