diff --git a/cocos/2d/CCSprite.cpp b/cocos/2d/CCSprite.cpp
index b9d813b..54331a9 100644
--- a/cocos/2d/CCSprite.cpp
+++ b/cocos/2d/CCSprite.cpp
@@ -4,6 +4,7 @@ Copyright (c) 2010-2012 cocos2d-x.org
 Copyright (c) 2011      Zynga Inc.
 Copyright (c) 2013-2016 Chukong Technologies Inc.
 Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.
+Copyright (c) 2021 cocos2d-lua.org
 
 http://www.cocos2d-x.org
 
@@ -472,9 +473,14 @@ void Sprite::updateProgramStateTexture()
     auto programState = _trianglesCommand.getPipelineDescriptor().programState;
     programState->setTexture(_textureLocation, 0, _texture->getBackendTexture());
     auto alphaTexture = _texture->getAlphaTexture();
-    if(alphaTexture && alphaTexture->getBackendTexture())
-    {
-        programState->setTexture(_alphaTextureLocation, 1, alphaTexture->getBackendTexture());
+    // may ETC1 or user defined shader used u_texture1.
+    if (_alphaTextureLocation.location[0] != -1 || _alphaTextureLocation.location[1] != -1) {
+        if(alphaTexture && alphaTexture->getBackendTexture()) {
+            programState->setTexture(_alphaTextureLocation, 1, alphaTexture->getBackendTexture());
+        } else {
+            // set a default texture into location to make metal render happy.
+            programState->setTexture(_alphaTextureLocation, 1, _texture->getBackendTexture());
+        }
     }
 }
 
diff --git a/cocos/renderer/backend/metal/ShaderModuleMTL.mm b/cocos/renderer/backend/metal/ShaderModuleMTL.mm
index d0f8291..5e35eba 100644
--- a/cocos/renderer/backend/metal/ShaderModuleMTL.mm
+++ b/cocos/renderer/backend/metal/ShaderModuleMTL.mm
@@ -1,5 +1,6 @@
 /****************************************************************************
  Copyright (c) 2018-2019 Xiamen Yaji Software Co., Ltd.
+ Copyright (c) 2021 cocos2d-lua.org
 
  http://www.cocos2d-x.org
 
@@ -37,22 +38,16 @@ ShaderModuleMTL::ShaderModuleMTL(id<MTLDevice> mtlDevice, ShaderStage stage, con
     glslopt_ctx* ctx = glslopt_initialize(kGlslTargetMetal);
     glslopt_shader_type shaderType = stage == ShaderStage::VERTEX ? kGlslOptShaderVertex : kGlslOptShaderFragment;
     glslopt_shader* glslShader = glslopt_optimize(ctx, shaderType, source.c_str(), 0);
-    if (!glslShader)
-    {
-        NSLog(@"Can not translate GLSL shader to metal shader:");
-        NSLog(@"%s", source.c_str());
-        return;
-    }
-    
-    const char* metalShader = glslopt_get_output(glslShader);
-    if (!metalShader)
-    {
+    if (!glslopt_get_status(glslShader)) {
         NSLog(@"Can not get metal shader:");
         NSLog(@"%s", source.c_str());
+        NSLog(@"%s", glslopt_get_log(glslShader));
+        glslopt_shader_delete(glslShader);
         glslopt_cleanup(ctx);
         return;
     }
     
+    const char* metalShader = glslopt_get_output(glslShader);
 //    NSLog(@"%s", metalShader);
     
     parseAttibute(mtlDevice, glslShader);
@@ -66,8 +61,7 @@ ShaderModuleMTL::ShaderModuleMTL(id<MTLDevice> mtlDevice, ShaderStage stage, con
     id<MTLLibrary> library = [mtlDevice newLibraryWithSource:shader
                                                      options:nil
                                                        error:&error];
-    if (!library)
-    {
+    if (!library) {
         NSLog(@"Can not compile metal shader: %@", error);
         NSLog(@"%s", metalShader);
         glslopt_shader_delete(glslShader);
@@ -79,8 +73,7 @@ ShaderModuleMTL::ShaderModuleMTL(id<MTLDevice> mtlDevice, ShaderStage stage, con
         _mtlFunction = [library newFunctionWithName:@"xlatMtlMain1"];
     else
         _mtlFunction = [library newFunctionWithName:@"xlatMtlMain2"];
-    if (!_mtlFunction)
-    {
+    if (!_mtlFunction) {
         NSLog(@"metal shader is ---------------");
         NSLog(@"%s", metalShader);
         assert(false);