Common errors and what they mean to me

Some .NET errors make a lot of sense. For example,

"There are more columns in the INSERT statement than values specified in the VALUES clause. The number of values in the VALUES clause must match the number of columns specified in the INSERT statement."

Thank You! I know exactly what is up with that. However, others are less clear. I'm gonna start a list here of cryptic errors and the most common reasons for why they occur (at least to me). This will probably reflect *my* weaknesses as a programmer rather than anything actually related to the error : )

System.Data.SqlClient.SqlException: Incorrect syntax near '.'.
-- this means you forgot a comma in a list in the SQL statement - probably after the penultimate item.

Object reference not set to an instance of an object.
-- this means you don't even have a NULL value for something. You don't actually have the something.
-- look for variable declarations.

And finally, some error messages are just plan hi-larious:

'success' does not exist in the current context

Thanks for the zen tip!