Today I received the following error after editing the endpoint url in my apex class:

System.CalloutException: Web service callout failed: Unable to find Apex package

I got this error once before and burned an entire day attempting every viable solution i found on these forums.  Nothing worked.  The next day i tested the solution and everything immidiately worked as it should.  So my question: Is this a salesforce issue that pops up its annoying head every once in awhile or is there something about apex classes which i am not fully understanding?  And if it is due to my lack of understanding, can someone point me the way to greater enlightenment?

Today I received the following error after editing the endpoint url in my apex class:

System.CalloutException: Web service callout failed: Unable to find Apex package

I got this error once before and burned an entire day attempting every viable solution i found on these forums.  Nothing worked.  The next day i tested the solution and everything immidiately worked as it should.  So my question: Is this a salesforce issue that pops up its annoying head every once in awhile or is there something about apex classes which i am not fully understanding?  And if it is due to my lack of understanding, can someone point me the way to greater enlightenment?