Zend Server Best Practices > Development > Monitoring Rules > Function Error

Function Error

Description: When a specific function in your code returns FALSE, it generates an event. The “Function Error” Rule contains a list of monitored functions (i.e. functions that when returning FALSE will trigger an event).

Information Collected:

The most important details are:

Function Name - As displayed in the Issue’s General Details
Function Arguments - The arguments of the function that triggered the event are listed in the Function Data tab.
Backtrace – identify what happened before the error happened that may have caused a problem such as incorrect data or problematic input data.

In most cases, these details alone should be enough to indicate what triggered the event.

Applicable Diagnostic Actions:

Click on a link to see how to perform each action tools are listed in order of relevance to helping solve the event:

Run the Debugger
Open code in editor
Redefine database queries
View information in the Logs
Run the Profiler

Possible Causes and Solutions:

Generally, logic errors trigger Function Error eventsAn event is a collection of runtime-related information collected by the Monitor component. This information is collected when an event is triggered, according to the conditions defined by the Monitoring Rules. such as queries that you expect to return something and they do not and not PHP errors.

If you have a function that you need to return FALSE as an acceptable value, remove the function from the monitored functions list.

Internal PHP functions – If you are using internal PHP functions, the best reference for investigating the problem is use the PHP manual.
You can also check your logs to see if they show PHP error information logged the same time the function error occurred.
User define functions – If it is a user defined function, running the debugger will help find out if the function is running complicated actions that are causing the function to fail. Using Breakpoints while debugging, will further pinpoint the problematic area in the code.
False Positives - Sometimes functions are supposed to return FALSE. Not all functions that return FALSE are indicative of a problem in your code or environment and they may be no indication of unacceptable behavior. If this is the case, remove the function from the Rule’s “Event Condition” list or set the status of issues triggered by this function to ignored.

Note:

Removing a function from the rule, affects all instances of the function. Before removing the function from the list, make sure the function does not require monitoring wherever it is used.

	Read Also
	Advanced Diagnostics with Zend Server
	Monitoring Rules