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## ⁠6.2. Runtime Errors and Warnings

Runtime errors and warnings occur when the SystemTap instrumentation has been installed and is collecting data on the system.

### ⁠WARNING: Number of errors: N, skipped probes: M

Errors and/or skipped probes occurred during this run. Both N and M are the counts of the number of probes that were not executed due to conditions such as too much time required to execute event handlers over an interval of time.

### ⁠division by 0

The script code performed an invalid division.

### ⁠aggregate element not found

A statistics extractor function other than `@count` was invoked on an aggregate that has not had any values accumulated yet. This is similar to a division by zero.

### ⁠aggregation overflow

An array containing aggregate values contains too many distinct key pairs at this time.

### ⁠MAXNESTING exceeded

Too many levels of function call nesting were attempted. The default nesting of function calls allowed is 10.

### ⁠MAXACTION exceeded

The probe handler attempted to execute too many statements in the probe handler. The default number of actions allowed in a probe handler is 1000.

### ⁠kernel/user string copy fault at ADDR

The probe handler attempted to copy a string from kernel or user space at an invalid address (ADDR).

### ⁠pointer dereference fault

There was a fault encountered during a pointer dereference operation such as a target variable evaluation.

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