Before making changes to your source code always take a backup copy of the original in case anything should go wrong. You are recommended to choose lower case file names for files on Unix systems. You may like to strip sequence numbers from Fortran source files. If you get reams of error messages, then look through the file with an editor, something may have gone wrong in the transfer. Some of the more common problems and their solutions are described here.
More information is available.
Some compilers keep to the standard. A Sun Fortran compiler, for example, will produce misleading messages about statements extending beyond column 72 and missing apostrophies. If this occurs then you must edit your code to conform to the standard. If you use any libraries , such as GINO or NAG, then you may need further information. Any error messages at this stage are probably due to missing library routines, double check that you are calling the appropriate libraries.