AI-generated Key Takeaways
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          The page provides a list of services within the Ad Manager API, including links to their documentation. 
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          It details the NotNullError.Reasonenumeration, which outlines possible reasons for a target error, such as null arguments or an unknown reason.
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          The enumeration includes specific values like ARG1_NULL,ARG2_NULL,ARG3_NULL,NULL, andUNKNOWNto indicate the cause of the null error.
The reasons for the target error.
- Namespace
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               https://www.google.com/apis/ads/publisher/v202508
| Enumeration | Description | 
|---|---|
| ARG1_NULL | Assuming that a method will not have more than 3 arguments, if it does, return NULL | 
| ARG2_NULL | |
| ARG3_NULL | |
| NULL | |
| UNKNOWN | The value returned if the actual value is not exposed by the requested API version. |