Why does the OAuth Unauthorized Error (401) happen?

Sometimes an Twitter OAuth is successfully executed, but an unauthorized error is thrown. I get about 50 of these on a daily basis. It is worrying, because I have no idea how that might be reproduced.

What are the different cases where this error happens, and how开发者_JAVA技巧 can this be fixed or prevented?

Twitter has been having a lot of issues lately, also I have noticed to ensure good pass through i use HTTPS, and ensure my domain is api.twitter.com

and that remote path is using the /1/ prefix example: /1/statuses/update.xml