Just chiming in regarding your remark on the URL 403 issue and KEGGREST: I also recently repeatedly experienced this 'error 'while using the KEGGREST package, and I reached out to the KEGG helpdesk. They informed me that this is indeed due to a protection system that is activated when too many requests are made to their server.

Hello, I would like to query the KEGG database in R using the Bioconductor library KEGGREST.
However, since the last couple of days I noticed that my code doesn't work anymore. I always get an error "Forbidden (HTTP 403)."

When manually copying the generated URL in my webbrowser I do observe the same error.
That is, the link:
https://rest.kegg.jp/pathway/hsa

results in:
"Forbidden
You don't have permission to access this resource.
Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request."

Any idea on what may be going on? Did something change on the server that may cause this?

Thank you,


-+-+
     We are sorry for the inconvenience.
    Our server is configured to consider intermittent accesses as an attack as a countermeasure against DDoS attacks.

    Your IP addres xxx.xxx.xxx.xx is denied access by the server.

    The criteria are as follows:
    1) When there are 240 accesses within 60 seconds of the last access,
       the SuspectDoS environment variable is set to "1".
    2) When there are 240 additional accesses within 3600 seconds,
       our server denies access from the corresponding IP address.
    3) When there are no accesses for the next 3600 seconds,
       the counter will return to 0.
    4) If there is another access within 3600 seconds of the last access,
       the counter continues to add.

    Please consider the frequency of access based on the above.

    Sincerely,
    ....