Yahoo - Error 999

Yesterday I finally received the coveted “Error 999” page from Yahoo:

Sorry, Unable to process request at this time -- error 999.
Unfortunately we are unable to process your request at this time. This error is usually temporary. Please try again later.
If you continue to experience this error, it may be caused by one of the following:

1. You may want to scan your system for spyware and viruses, as they may interfere with your ability to connect to Yahoo!. For detailed information on spyware and virus protection, please visit the Yahoo! Security Center.


2. This problem may be due to unusual network activity coming from your Internet Service Provider. We recommend that you report this problem to them.

While this error is usually temporary, if it continues and the above solutions don't resolve your problem, please let us know.

Just like Google, Yahoo appears to also be monitoring for high volume traffic/automated requests and denying access for a period of time from infringing IP addresses.

I have a couple of scripts that make 300 queries per day to Yahoo using their web interface. 126 of my queries received the error yesterday, and 125 today. The scripts ran for 11 days before being detected. You’d think 300 queries wouldn’t be enough to trigger the response! I’m also making the 300 same queries using the API to see what the difference is in their responses.

I’ve seen others complain of the 999 error dating back to April 2004, but this is the first time I have personally experienced it. Murray Moffatt shares his experience with the error and some possible fixes. Basically all you can do if you are running a script and encounter the page is to sleep for several minutes and try again.

Update: 6/9/06

Today I increased the wait time between each query to a random number of seconds between 3-8. I also ran the script at 8:00 am EST instead of 2:00 am EST to see if blending into the croud helped at all. Today I received 133 error 999s. Not good. Possibly I'm being punished because I'm making requests at a high volume time. Next: increase the wait time to 15-20 seconds between each query.