Deprecated **X509Cert.getSerialNumber()** and replaced it with **X509Cert.getCertSerialNumber()**.
**Change Impact**
**X509Cert.getSerialNumber()** is deprecated since API version 10. **X509Cert.getCertSerialNumber()** should be used to replace **X509Cert.getSerialNumber()** in application development. The API function remains unchanged.
**Key API/Component Changes**
API before change:
```js
interfaceX509Cert{
...
getSerialNumber():number;
...
}
```
API after change:
```js
interfaceX509Cert{
...
getCertSerialNumber():bigint;
...
}
```
**Adaptation Guide**
See [Certificate Development Guide](../../../application-dev/security/cert-guidelines.md) and [Certificate](../../../application-dev/reference/apis/js-apis-cert.md).