Error when executing VTA tutorials (deploy_classification and tune_relay_vta)

When I run the VTA tutotial Deploy Pretrained Vision Model from MxNet on VTA and Auto-tuning a convolutional network on VTA, it throwed errors as follows. For classification:

Traceback (most recent call last):

  File "/Users/zqh/tvm/vta/tutorials/frontend/deploy_classification.py", line 200, in <module>
    params=params, target_host=env.target_host)

  File "/Users/zqh/tvm/python/tvm/relay/build_module.py", line 250, in build
    graph_json, mod, params = bld_mod.build(mod, target, target_host, params)

  File "/Users/zqh/tvm/python/tvm/relay/build_module.py", line 119, in build
    self._build(mod, target, target_host)

  File "/Users/zqh/tvm/python/tvm/_ffi/_ctypes/packed_func.py", line 213, in __call__
    raise get_last_ffi_error()

tvm._ffi.base.TVMError: Traceback (most recent call last):
  [bt] (8) 9   libtvm.dylib                        0x000000012faa373e tvm::relay::backend::GraphRuntimeCodegenModule::GetFunction(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, tvm::runtime::ObjectPtr<tvm::runtime::Object> const&)::'lambda0'(tvm::runtime::TVMArgs, tvm::runtime::TVMRetValue*)::operator()(tvm::runtime::TVMArgs, tvm::runtime::TVMRetValue*) const + 78
  [bt] (7) 8   libtvm.dylib                        0x000000012faa3e95 tvm::relay::backend::GraphRuntimeCodegen::Codegen(tvm::relay::Function) + 1637
  [bt] (6) 7   libtvm.dylib                        0x000000012faa515d tvm::relay::backend::GraphRuntimeCodegen::GetJSON(dmlc::JSONWriter*) + 1901
  [bt] (5) 6   libtvm.dylib                        0x000000012faa7afb void dmlc::JSONWriter::WriteObjectKeyValue<std::__1::vector<std::__1::shared_ptr<tvm::relay::backend::GraphNode>, std::__1::allocator<std::__1::shared_ptr<tvm::relay::backend::GraphNode> > > >(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::vector<std::__1::shared_ptr<tvm::relay::backend::GraphNode>, std::__1::allocator<std::__1::shared_ptr<tvm::relay::backend::GraphNode> > > const&) + 187
  [bt] (4) 5   libtvm.dylib                        0x000000012faa869f dmlc::json::ArrayHandler<std::__1::vector<std::__1::shared_ptr<tvm::relay::backend::GraphNode>, std::__1::allocator<std::__1::shared_ptr<tvm::relay::backend::GraphNode> > > >::Write(dmlc::JSONWriter*, std::__1::vector<std::__1::shared_ptr<tvm::relay::backend::GraphNode>, std::__1::allocator<std::__1::shared_ptr<tvm::relay::backend::GraphNode> > > const&) + 335
  [bt] (3) 4   libtvm.dylib                        0x000000012faa033a tvm::relay::backend::GraphOpNode::Save(dmlc::JSONWriter*) const + 1626
  [bt] (2) 3   libtvm.dylib                        0x000000012faa087b void dmlc::JSONWriter::WriteObjectKeyValue<std::__1::unordered_map<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, dmlc::any, std::__1::hash<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::equal_to<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, dmlc::any> > > >(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::unordered_map<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, dmlc::any, std::__1::hash<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::equal_to<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, dmlc::any> > > const&) + 187
  [bt] (1) 2   libtvm.dylib                        0x000000012faa106c dmlc::json::Handler<std::__1::unordered_map<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, dmlc::any, std::__1::hash<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::equal_to<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, dmlc::any> > > >::Write(dmlc::JSONWriter*, std::__1::unordered_map<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, dmlc::any, std::__1::hash<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::equal_to<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, dmlc::any> > > const&) + 508
  [bt] (0) 1   libtvm.dylib                        0x000000012f272289 dmlc::LogMessageFatal::~LogMessageFatal() + 57
  File "/Users/zqh/tvm/src/relay/backend/graph_runtime_codegen.cc", line 732
TVMError: Not supported

and for tune_relay_vta:

Extract tasks...
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/Users/zqh/miniconda3/envs/tvm/lib/python3.7/threading.py", line 926, in _bootstrap_inner
    self.run()
  File "/Users/zqh/miniconda3/envs/tvm/lib/python3.7/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/Users/zqh/tvm/python/tvm/autotvm/task/relay_integration.py", line 49, in _lower
    grc.codegen(mod["main"])
  File "/Users/zqh/tvm/python/tvm/relay/backend/graph_runtime_codegen.py", line 82, in codegen
    self._codegen(func)
  File "/Users/zqh/tvm/python/tvm/_ffi/_ctypes/packed_func.py", line 213, in __call__
    raise get_last_ffi_error()
tvm._ffi.base.TVMError: Traceback (most recent call last):
  [bt] (8) 9   libtvm.dylib                        0x0000000139d6b73e tvm::relay::backend::GraphRuntimeCodegenModule::GetFunction(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, tvm::runtime::ObjectPtr<tvm::runtime::Object> const&)::'lambda0'(tvm::runtime::TVMArgs, tvm::runtime::TVMRetValue*)::operator()(tvm::runtime::TVMArgs, tvm::runtime::TVMRetValue*) const + 78
  [bt] (7) 8   libtvm.dylib                        0x0000000139d6be95 tvm::relay::backend::GraphRuntimeCodegen::Codegen(tvm::relay::Function) + 1637
  [bt] (6) 7   libtvm.dylib                        0x0000000139d6d15d tvm::relay::backend::GraphRuntimeCodegen::GetJSON(dmlc::JSONWriter*) + 1901
  [bt] (5) 6   libtvm.dylib                        0x0000000139d6fafb void dmlc::JSONWriter::WriteObjectKeyValue<std::__1::vector<std::__1::shared_ptr<tvm::relay::backend::GraphNode>, std::__1::allocator<std::__1::shared_ptr<tvm::relay::backend::GraphNode> > > >(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::vector<std::__1::shared_ptr<tvm::relay::backend::GraphNode>, std::__1::allocator<std::__1::shared_ptr<tvm::relay::backend::GraphNode> > > const&) + 187
  [bt] (4) 5   libtvm.dylib                        0x0000000139d7069f dmlc::json::ArrayHandler<std::__1::vector<std::__1::shared_ptr<tvm::relay::backend::GraphNode>, std::__1::allocator<std::__1::shared_ptr<tvm::relay::backend::GraphNode> > > >::Write(dmlc::JSONWriter*, std::__1::vector<std::__1::shared_ptr<tvm::relay::backend::GraphNode>, std::__1::allocator<std::__1::shared_ptr<tvm::relay::backend::GraphNode> > > const&) + 335
  [bt] (3) 4   libtvm.dylib                        0x0000000139d6833a tvm::relay::backend::GraphOpNode::Save(dmlc::JSONWriter*) const + 1626
  [bt] (2) 3   libtvm.dylib                        0x0000000139d6887b void dmlc::JSONWriter::WriteObjectKeyValue<std::__1::unordered_map<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, dmlc::any, std::__1::hash<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::equal_to<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, dmlc::any> > > >(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::unordered_map<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, dmlc::any, std::__1::hash<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::equal_to<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, dmlc::any> > > const&) + 187
  [bt] (1) 2   libtvm.dylib                        0x0000000139d6906c dmlc::json::Handler<std::__1::unordered_map<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, dmlc::any, std::__1::hash<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::equal_to<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, dmlc::any> > > >::Write(dmlc::JSONWriter*, std::__1::unordered_map<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, dmlc::any, std::__1::hash<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::equal_to<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, dmlc::any> > > const&) + 508
  [bt] (0) 1   libtvm.dylib                        0x000000013953a289 dmlc::LogMessageFatal::~LogMessageFatal() + 57
  File "/Users/zqh/tvm/src/relay/backend/graph_runtime_codegen.cc", line 732
TVMError: Not supported

The system is macos 10.14.6 and TVM version is 0.7.dev1. Can someone please help me with this? Thanks. @tqchen @thierry