According to the XST User Guide, the following format for the ".prj" file is supported:
[Language] [library name] [file name]
However,modifying the project to be specifically VHDL orVerilog rather than MIXED, results in the following error:
"ERROR:Xst:2750 - line 1: Bad project format. Valid format is '[library_name] file_name'"
If you have the project set up as VHDL or Verilog, then the format should be:
[Library name] [file name]
This error occurs only with the new XST Parser which did not provide consistent behavior while handling different formats. This works with XST if targeting Virtex-5 or older devices.
Starting in 13.4, XST supports only mixed language format by default. Also,13.4 XST does not support the "-ifmt" switch. The "-ifmt" option has been removed from ISE 13.4 Project Navigator. The 13.4 XST user guide has also been updated with this change by removing the"-ifmt" option from the document.
In earlier versions, you can work around this issue by either choosing MIXED language, or modify the ".prj" file.