> For the complete documentation index, see [llms.txt](https://docs.exads.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.exads.com/api/ad-placement-api/ad-plac-errors.md).
# Errors
## HTTP Error Codes
| Code | Description | Explanation |
| ---- | -------------- | --------------------------------------------------------------------------------------------------------------------------------- |
| 400 | Bad Request | Indicates that the data sent is incorrectly formatted |
| 200 | OK | Indicates that the request is correct, but one or more zones could not be found. The response will tell you which zones these are |
| 500 | Internal Error | Indicates that an internal error happened but the cause is unknown. Support should be contacted |
## 400 Error Messages
| Message | Explanation |
| ------------------------ | ---------------------------------------------------------------- |
| Malformed JSON Body | The JSON is malformed in some way |
| Unsupported Request Type | For example, the request uses GET instead of POST |
| This field is missing | The field is missing or is incorrectly formatted for some reason |
## 200 Error Messages
| Message | Explanation |
| ---------------------- | ------------------------------------------ |
| Zone ID not found | The zone ID is not present in the database |
| Zone or site not valid | The zone or Publisher is blocked |
## Data Null
Very rarely, an ad zone request will return a correct response, but the `data` field will be null. This means that the system found no ads to satisfy the given request given user locale, browser etc.
---
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