1# Security Subsystem Changelog
2
3##  cl.cert.1 X509Cert.getSerialNumber Deprecated
4
5Deprecated **X509Cert.getSerialNumber()** and replaced it with **X509Cert.getCertSerialNumber()**.
6
7**Change Impact**
8
9Since API version 10, use **X509Cert.getCertSerialNumber()** instead of **X509Cert.getSerialNumber()** in application development. The API function remains unchanged.
10
11**Key API/Component Changes**
12
13Before change:
14
15 ```js
16interface X509Cert {
17  ...
18  getSerialNumber(): number;
19  ...
20}
21 ```
22
23After change:
24
25 ```js
26interface X509Cert {
27  ...
28  getCertSerialNumber(): bigint;
29  ...
30}
31 ```
32
33**Adaptation Guide**
34
35See [Certificate Development Guide](../../../application-dev/security/cert-guidelines.md) and [Certificate](../../../application-dev/reference/apis/js-apis-cert.md).
36