Q:

How to solve HTTP Error 429 in BioPython?

I'm trying to use BioPython to acquire nucleotide sequences by inputting accession number and start and end positions. I need to acquire many sequences but the process was aborted just after 3 sequences. I got this error:
"urllib.error.HTTPError: HTTP Error 429: Too Many Requests". 
Could it be that I used BioPython to run blast too many times previously? It took about three weeks to finish the alignments for my last task. Does it mean I have been blocked by the server?

A:

Please see this post about the use of API keys with NCBI e-utilities and add the API key to your scripts to avoid this error. 

