This error occurs when an attribute or line of code does not fall within a definition.
Correct the code with proper definition or check if certain characters are written by mistake.
Example
Use: Balance Sheet
[Report: MyReport]
In the above example the word Us: Balance Sheet not part of any definition. Hence the message appears as error T0027: The attribute definition started without a valid description.
The code is corrected by removing the word Use statement from the program.
[Report: MyReport]