Where to verify SAP Error Messages ?

[RovirozM]

Hi Guys,

Sometimes I receive messages as this one:

E847 - You cannot Change Item 000020

This is when I'm trying to post a Shipment.....

By my question is related about this:

Is there a place (Website or something else) where I can go and found more information related to this kind of errors ? "E847"

Something that can help and understand better "what to do" in order to fix it... or maybe know from where to start with possible options...

Thanks for any help or recommendation about this ! ;O)

MR