---
description: "Learn more about: Warning C26166"
title: Warning C26166
ms.date: 11/04/2016
f1_keywords: ["C26166"]
helpviewer_keywords: ["C26166"]
ms.assetid: a3d21838-07da-40f6-8d2e-1ada72765af2
---
# Warning C26166

> Possibly failing to acquire or to hold lock '*lock*' in function '*func*'.

Warning C26166 resembles warning [C26116](../code-quality/c26116.md) except that the confidence level is lower. For example, the function may contain annotation errors.

## Example

The following code shows code that will generate warning C26166.

```cpp
typedef struct _DATA {
CRITICAL_SECTION cs;
} DATA;

_Acquires_lock_(p->cs) void Enter(DATA* p) {
    EnterCriticalSection(&p->cs); // OK
}

_Acquires_lock_(p->cs) void BAD(DATA* p) {} // Warning C26166
```