Description
This internal error may be generated if you incorrectly specify your VHDL libraries as follows:
USE ieee.std_logic_1164..ALL;
 | In this example, the user has added an extra period (.) between 1164 and ALL. |
The actual library statement should read as follows:
USE ieee.std_logic_1164.ALL;
Using proper syntax when defining your libraries will allow you to avoid this error.