I’m not going to look in detail at your problem, but I do have the following superficial reacitons:

first one is, for the error message, good to include the full output, with all the stack trace, line numbers and so on. since this can be quite long https://gist.github.com 36 is quite good for this
I notice you are suggesting that ‘sequence length’ and ‘number of features’ are conceptually the same. Without looking at your own code, generally speaking:
– sequence length tends to correspond to the number of time steps you’re going to forward/back propagate over. For example, if you are using a char-level rnn, to predict the next character, and your input data is ‘welcom’, and the label is ‘e’, the sequence length here is 6: the 6 letters of ‘welcom’
– number of features corresponds to the number of dimensions of the input at each time step. if you’re feeding in one-hot characters, this is the number of possible characters, typically something of the order of 60-100 or so
– but the RNN itself has hidden layers, with possibly a different number of features
– and the output can have yet another number of features