dear @apmuthu, if that is the case, why did you ask me earlier to first "check the Trial Balances for any discrepancy and whether Credit and Debit balances tally." after that to "Test with Debian 6 and MySQL 5.1 and PHP 5.3.3" and to "take assistance of php programmers to inspect variables in the code at the point of failure where the error comes out." and finally stating that "adding a user was a real problem practically all major users of FA would have complained by now."
I clearly stated that, " this happens with a fresh new installation of FrontAccounting". So the issue is a rights issue that I was not aware of that "has been the default since the very beginning over 15 years ago.": The System Administrator does not have the rights to close by default. A simple review of rights solved the issue.
I am writing this, because you seem to mass-answer questions on this forum. This mass-answering might be the reason, why your answers (at least in my case but potentially in other posts that I have seen in the forum) seem to miss the connection to the underlying issue. Maybe answer a little bit less and in instead focus more on moving towards the solution?
While I am extremely grateful for your huge commitment and your energy, I feel that at least in this case, your comments more obstructed the solution than helping to move toward the solution. Anybody reading this because she or he was looking for a solution to the problem might be better off with just the solution of @fburbano without all the tangents/distractions that you introduced.