diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 1c5abf4d01a29..e4a9d5c259a91 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -13429,6 +13429,16 @@ void GLES2DecoderImpl::DoCopyTexImage2D(
     return;
   }
 
+  if (GetBoundFramebufferSamples(GL_READ_FRAMEBUFFER) > 0) {
+    // Per ES 3.0 §8.6, copying from a multisampled read framebuffer generates
+    // GL_INVALID_OPERATION. Reject here so that the clipped branch below
+    // cannot redefine the driver-side level via glTexImage2D and then have
+    // glCopyTexSubImage2D fail, leaving the decoder LevelInfo stale.
+    LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, func_name,
+                       "multisampled framebuffer");
+    return;
+  }
+
   GLenum read_format = GetBoundReadFramebufferInternalFormat();
   GLenum read_type = GetBoundReadFramebufferTextureType();
   if (!ValidateCopyTexFormat(func_name, internal_format,