Read through the available output files to find out where the execution stopped. Use that as a key as to where to look at potential input problems.

If there are words referring to a unit number, determine which type of information is the problem by identifying the input associated with that unit.

Carefully read the error message, "clinging" to any word that might tip you off to the location of the problem.

View your input files in an editor that will reveal codes for spaces and tabs. Replace all tabs with spaces.

Ensure that there is a carriage return at the end of the last line of each file.

If no output files are created, then confirm that your command line or batch file are correct. If these are correct, work through the input line by line. For MODFLOW, start with the nam and bas files.

The worst situation is when all the input seems to be fine and its echo to the output file seems to be fine right up to when the solution begins.

At this point you need to "burn neurons" in an attempt to determine what you might you have done that doesn't make hydrologic sense or computer sense. BEWARE the trap of thinking "I have done everything correctly" and instead think "What have I done incorrectly"?