# .NET Error

If you receive an error that looks like this:

<figure><img src="https://2867813904-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F1J5Yx5LRM1m9ejaniuNB%2Fuploads%2F6yVqEJWEWcQy7N0ZZLoc%2Fimage.png?alt=media&#x26;token=2b585c5d-10cc-4b37-a782-c34f413ca990" alt=""><figcaption></figcaption></figure>

Navigate to your Build Settings (CMD-Shift-B), select Player Settings at the bottom-right corner:

&#x20;

<figure><img src="https://2867813904-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F1J5Yx5LRM1m9ejaniuNB%2Fuploads%2F4fgXFakDLOc8YugrkApc%2Fimage.png?alt=media&#x26;token=68ea50a3-f791-4d71-bab9-61fba9624134" alt=""><figcaption></figcaption></figure>

In the iOS section (which should be selected by default), drop down the "Other Settings" section, scroll down to the "Configuration" section, and ensure that the Api Compatibility Level is set to .NET 4.x:

&#x20;

<figure><img src="https://2867813904-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F1J5Yx5LRM1m9ejaniuNB%2Fuploads%2FrVnqwxEz9ZuWXC1BLB0X%2Fimage.png?alt=media&#x26;token=bc80218c-adaa-4341-afea-c88c9ac8d926" alt=""><figcaption></figcaption></figure>

Note that this is only an issue on older versions of the Unity editor, as newer versions will use .NET Standard 2.1, which is compatible with our library.