If a file system task such as a rename fails, for example if the file does not exist, then this is considered an error by SSIS. This means the whole package fails. I can get aro
Check the FailPackageOnFailure and FailParentOnFailure properties of the FileSystem task and make sure they are set to False. Also, increase the MaximumErrorCount property of the package.
This combination will allow the task to fail and the package to still complete successfully.
Use a expression and constraint combination on the "precedence constraint" connector. return success always from your previous task (it may be a script looking for the file) and if file found, set a variable. in the expression of the "precedence constraint" check for the variable value and return true or false. If your expression evaluates to false, the package will nto continue and yet you will not see any error. - Mayukh
Make the property "Force execution Result" to success for the File system task..