--- a/dom/canvas/WebGLTextureUpload.cpp
+++ b/dom/canvas/WebGLTextureUpload.cpp
@@ -1751,25 +1751,16 @@ WebGLTexture::CopyTexImage2D(TexImageTar
     if (!mContext->ValidateCurFBForRead(funcName, &srcUsage, &srcWidth, &srcHeight,
                                         &srcMode))
         return;
     auto srcFormat = srcUsage->format;
 
     if (!ValidateCopyTexImageForFeedback(funcName, level))
         return;
 
-    // GLES 3.0.4 p145:
-    // "Calling CopyTexSubImage3D, CopyTexImage2D, or CopyTexSubImage2D will result in an
-    //  INVALID_OPERATION error if any of the following conditions is true: READ_BUFFER
-    //  is NONE"
-    if (srcMode == LOCAL_GL_NONE) {
-        mContext->ErrorInvalidOperation("%s: READ_BUFFER is NONE. ", funcName);
-        return;
-    }
-
     ////////////////////////////////////
     // Check that source and dest info are compatible
 
     const auto& fua = mContext->mFormatUsage;
 
     auto dstUsage = fua->GetSizedTexUsage(internalFormat);
     if (!dstUsage) {
         // It must be an unsized format then...
@@ -1915,25 +1906,16 @@ WebGLTexture::CopyTexSubImage(const char
     if (!mContext->ValidateCurFBForRead(funcName, &srcUsage, &srcWidth, &srcHeight,
                                         &srcMode))
         return;
     auto srcFormat = srcUsage->format;
 
     if (!ValidateCopyTexImageForFeedback(funcName, level))
         return;
 
-    // GLES 3.0.4 p145:
-    // "Calling CopyTexSubImage3D, CopyTexImage2D, or CopyTexSubImage2D will result in an
-    //  INVALID_OPERATION error if any of the following conditions is true: READ_BUFFER
-    //  is NONE"
-    if (srcMode == LOCAL_GL_NONE) {
-        mContext->ErrorInvalidOperation("%s: READ_BUFFER is NONE. ", funcName);
-        return;
-    }
-
     ////////////////////////////////////
     // Check that source and dest info are compatible
 
     if (!ValidateCopyTexImageFormats(mContext, funcName, srcFormat, dstFormat))
         return;
 
     ////////////////////////////////////
     // Do the thing!