Operation not available: Mattel

InvalidArgumentError: Cannot assign a device for operation don_nn/model_2/branch_hidden0/MatMul/ReadVariableOp: Could not satisfy explicit device specification '' because the node {{colocation_node don_nn/model_2/branch_hidden0/MatMul/ReadVariableOp}} was colocated with a group of nodes that required incompatible device '/job:localhost/replica:0/task:0/device:GPU:0'. All available devices [/job:localhost/replica:0/task:0/device:CPU:0, /job:localhost/replica:0/task:0/device:GPU:0].