I need to add a new dataset to an already existing group in an already existing hdf5 file. I’m using the H5Cpp api and am getting errors like:

  #004: H5VLnative_dataset.c line 403 in H5VL__native_dataset_write(): unable to set up file and memory dataspaces
    major: Dataset
    minor: Unable to initialize object
  #005: H5VLnative_dataset.c line 177 in H5VL__native_dataset_io_setup(): selection + offset not within extent for file dataspace
    major: Dataspace
    minor: Out of range

I’ve gotten successful writes and appends to file without using group. Here’s a general method of what I have so far: Check if the group exists. If it does, open the group. Set the dataset size and dataspace, properties list, and fill value. Then I create the dataset using those parameters. After, write the data. I guess my main question: Is there a need to extend this size of a group?