Cannot reference column renamed to Week#(2) in Power Query (invalid identifier)

Hi T1moris 

Power Query has two different concepts:

Display name (what you see in the UI) => Week#(2)

M language identifier (what the engine must use internally)

M has strict identifier rules. A column name can be referenced directly only if it: Starts with a letter or underscore and Contains only letters, numbers, and underscores

Your column name: Week#(2) violates three rules: # is special in M ( and ) are not allowed in identifiers

In M: #"Some Text" means “treat this text literally as a name” So when Power Query internally generates: "Week#(#)(2)"

The column name contains literal text Week#(2), and the # itself must be escaped This is not a rename mistake—it’s Power Query protecting itself from syntax errors.

Why do [Week#(2)] and [Week#(#)(2)] both fail?
Because square brackets only work for valid identifiers. This works: [SalesAmount] and This fails: [Week#(2)]

Because Week#(2) is not a valid identifier, even if that looks like the column name.

The CORRECT way to reference this column is: [#"Week#(2)"]