Comment 17 for bug 1023047

Fast way to solve this problem

go in project_timesheet/prohect-timesheet.py
class project_work
def write

Near the end of the function you will see that,

self.pool.get('hr.analytic.timesheet').write(cr, uid, [line_id.id], vals_line, context=context)

Change like that
if vals_line:
    self.pool.get('hr.analytic.timesheet').write(cr, uid, [line_id.id], vals_line, context=context)

Why: Openerp have only the fields {'task_id': 6} in vals, so when he build vals_line, val_line is empty and try to do a write with NO fields in, and if val_line before do the write solve the problem for us.