> Documentation index: https://firebase.google.com/docs/analytics/llms.txt

| Error Code | Cause | Value | Result |
|---|---|---|---|
| 2 | Event name is invalid (empty, too long, invalid characters) | Name of the invalid event | The event is ignored and an `error` event is logged with a `firebase_error_value` parameter which indicates the invalid event name. |
| 3 | Event parameter name is invalid (empty, too long, invalid characters) | Name of the invalid parameter | The event parameter is replaced with a `firebase_error` parameter (one per event) and a `firebase_error_value` parameter is added to indicate the invalid parameter name. |
| 4 | Event parameter value is too long | Name of invalid parameter | The invalid parameter is dropped. A `firebase_error` parameter is added to the event and a `firebase_error_value` parameter is added to indicate the name of the parameter with the invalid value. |
| 5 | Event has more than 25 parameters | None | Extra event parameters are dropped. A `firebase_error` parameter is added to the event with the value of the error code. |
| 6 | User property name is invalid (empty, too long, invalid characters) | Name of invalid property. | The user property change is ignored. An `error` event is logged with a `firebase_error_value` parameter which indicates the invalid user property name. |
| 7 | User property value is too long | Name of invalid property. | The user property change is ignored. An `error` event is logged with a parameter whose value indicates the name of the invalid user property value. |
| 8 | App Instance logs more than 500 unique event types | None | Extra events are dropped. An `error` event is logged with a `firebase_error` parameter which indicates the error code. |
| 9 | App Instance sets more than 25 unique user properties | None | The user property change is ignored. An `error` event is logged with a `firebase_error` parameter which indicates the error code. |
| 10 | App Instance exceeds conversion event limit in a single day | None | Event is logged as a normal (i.e. non-conversion) event. A `firebase_error` parameter is added to the event with the value of the error code. |
| 11 | App Instance logs blocked event | Name of blocked event | Event is ignored. An `error` event is logged with a `firebase_error_value` parameter which indicates the blocked event name. |
| 12 | App Instance sets blocked user property. | Name of blocked user property. | The user property change is ignored. An `error` event is logged with a `firebase_error_value` parameter which indicates the blocked user property. |
| 13 | Event name is reserved | Name of reserved event. | Event is ignored. An `error` event is logged with a `firebase_error_value` parameter which indicates the invalid event name. |
| 14 | Event parameter name is reserved. | Name of reserved parameter. | Event parameter is replaced with a `firebase_error` parameter with the value of the error code. A `firebase_error_value` parameter is added to indicate the reserved parameter name. |
| 15 | User property name is reserved | Name of reserved user property | The user property change is ignored. An `error` event is logged with a `firebase_error_value` parameter which indicates the invalid user property name. |
| 17 | Parameter array length exceeds limit (200) | Name of truncated parameter array (value) | The array parameter is truncated to 200 items. A `firebase_error` parameter is added to the event (one per event) with the value of the error code. A `firebase_error_value` parameter is added to indicate the name of the truncated parameter. |
| 18 | Missing or invalid value parameter type | Name of missing or invalid parameter (value) | The value parameter is dropped. A `firebase_error` parameter is added to the event and a `firebase_error_value` parameter is added to indicate the name of the parameter that is missing or contains an invalid type (value). |
| 19 | Missing currency parameter on a conversion event | Name of invalid parameter (value) | The value parameter is dropped. A `firebase_error` parameter is added to the event and a `firebase_error_value` parameter is added to indicate the name of the invalid parameter (value). |
| 20 | Event array parameter name is invalid | Name of invalid parameter (value) | The event parameter is replaced with a `firebase_error` parameter (one per event) and a `firebase_error_value` parameter is added to indicate the invalid parameter name. |
| 21 | Event does not support array parameters | Name of the invalid event | The event parameter is replaced with a `firebase_error` parameter (one per event) and a `firebase_error_value` parameter is added to indicate the invalid event name. |
| 22 | Item cannot contain an array-based parameter | Name of invalid parameter (value) | The nested array parameter is replaced with a `firebase_error` parameter (one per param) and a `firebase_error_value` parameter is added to indicate the invalid param name. |
| 23 | Item cannot contain custom parameters | None | Custom array parameters are dropped. Add a `firebase_error` parameter with the value of the error code. |
| 25 | Item array not supported on client's version of Google Play Services (Android Only) | None | Array parameters are dropped. Add a `firebase_error` parameter with the value of the error code. |
| 28 | Item has more than 27 custom parameters | None | Extra item parameters are dropped. A `firebase_error` parameter is added to the item with the value of the error code. |

> [!NOTE]
> **Note:** When the Firebase SDK encounters issues with event names, parameters, or user properties, it logs an `error` event. `firebase_error` is an event parameter, not an event name. Both automatically generated `error` events and other events that include a `firebase_error` parameter appear in the [DebugView](https://firebase.google.com/docs/analytics/debugview.md.txt) report.

To confirm if `error` events are generated and to understand the cause, check
the device console logs while your application is in debug mode. The SDK
provides diagnostic messages related to these errors.