"Create kernel failed" in Tensorflow when mapping nodes to different devices - tensorflow

Question

I have done some manual graph partitioning in tensorFlow using a simple hash function to map the nodes on different (2) CPU devices.
When I map the whole graph on the first device or the second it works. (That is why I don't understand the error message "Create kernel failed").
Do you have any idea what is wrong?
However the following error occurs:
E tensorflow/core/framework/op_segment.cc:53] Create kernel failed: Invalid argument: AttrValue must not have reference type value of float_ref
for attr 'tensor_type'
; NodeDef: Variable/_9 = _Recv[_start_time=0, client_terminated=false, recv_device="/job:localhost/replica:0/task:0/cpu:0", send_device="/job:localhost/replica:0/task:0/cpu:1", send_device_incarnation=1, tensor_name="edge_10_Variable", tensor_type=DT_FLOAT_REF, _device="/job:localhost/replica:0/task:0/cpu:0"](^zeros/_11); Op<name=_Recv; signature= -> tensor:tensor_type; attr=tensor_type:type; attr=tensor_name:string; attr=send_device:string; attr=send_device_incarnation:int; attr=recv_device:string; attr=client_terminated:bool,default=false; is_stateful=true>
E tensorflow/core/common_runtime/executor.cc:334] Executor failed to create kernel. Invalid argument: AttrValue must not have reference type value of float_ref
for attr 'tensor_type'
; NodeDef: Variable/_9 = _Recv[_start_time=0, client_terminated=false, recv_device="/job:localhost/replica:0/task:0/cpu:0", send_device="/job:localhost/replica:0/task:0/cpu:1", send_device_incarnation=1, tensor_name="edge_10_Variable", tensor_type=DT_FLOAT_REF, _device="/job:localhost/replica:0/task:0/cpu:0"](^zeros/_11); Op<name=_Recv; signature= -> tensor:tensor_type; attr=tensor_type:type; attr=tensor_name:string; attr=send_device:string; attr=send_device_incarnation:int; attr=recv_device:string; attr=client_terminated:bool,default=false; is_stateful=true>
[[Node: Variable/_9 = _Recv[_start_time=0, client_terminated=false, recv_device="/job:localhost/replica:0/task:0/cpu:0", send_device="/job:localhost/replica:0/task:0/cpu:1", send_device_incarnation=1, tensor_name="edge_10_Variable", tensor_type=DT_FLOAT_REF, _device="/job:localhost/replica:0/task:0/cpu:0"](^zeros/_11)]]
Traceback (most recent call last):
File "/Users/larissa/Desktop/GraphPartSched/Theorie/TensorFlow/TensorFlow_Tutorials/MNIST_For_ML_Beginners.py", line 53, in <module>
sess.run(init)
File "/Users/larissa/tensorflowSource/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 717, in run
run_metadata_ptr)
File "/Users/larissa/tensorflowSource/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 915, in _run
feed_dict_string, options, run_metadata)
File "/Users/larissa/tensorflowSource/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 965, in _do_run
target_list, options, run_metadata)
File "/Users/larissa/tensorflowSource/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 985, in _do_call
raise type(e)(node_def, op, message)
tensorflow.python.framework.errors.InvalidArgumentError: AttrValue must not have reference type value of float_ref
for attr 'tensor_type'
; NodeDef: Variable/_9 = _Recv[_start_time=0, client_terminated=false, recv_device="/job:localhost/replica:0/task:0/cpu:0", send_device="/job:localhost/replica:0/task:0/cpu:1", send_device_incarnation=1, tensor_name="edge_10_Variable", tensor_type=DT_FLOAT_REF, _device="/job:localhost/replica:0/task:0/cpu:0"](^zeros/_11); Op<name=_Recv; signature= -> tensor:tensor_type; attr=tensor_type:type; attr=tensor_name:string; attr=send_device:string; attr=send_device_incarnation:int; attr=recv_device:string; attr=client_terminated:bool,default=false; is_stateful=true>
[[Node: Variable/_9 = _Recv[_start_time=0, client_terminated=false, recv_device="/job:localhost/replica:0/task:0/cpu:0", send_device="/job:localhost/replica:0/task:0/cpu:1", send_device_incarnation=1, tensor_name="edge_10_Variable", tensor_type=DT_FLOAT_REF, _device="/job:localhost/replica:0/task:0/cpu:0"](^zeros/_11)]]