Hello @xueraozhang321
We have comprehensive Single Cell tutorials! This a good one to use as a reference.
Exploring your data with Inspect AnnData object can be a good way to better understand what the data currently contains. Requesting to parse data that does not exist can lead to errors similar to yours but how to correct the error depends on what you have now.
Please give that a try! If you need help, you are welcome to share back the history with the problematic data/tool query and we can try with more specific feedback. 