Enum describing possible feed item errors.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v26/errors/feed_mapping_error.proto)

| Enums ||
|---|---|
| ## `ATTRIBUTE_FIELD_MAPPING_MISSING_FIELD` | The "field" oneof was not set in an AttributeFieldMapping. |
| ## `CANNOT_MODIFY_MAPPINGS_FOR_TYPED_FEED` | Mappings for typed feeds cannot be modified. |
| ## `CANNOT_OPERATE_ON_MAPPINGS_FOR_SYSTEM_GENERATED_FEED` | A feed mapping for a system generated feed cannot be operated on. |
| ## `FEED_ATTRIBUTE_TYPE_MISMATCH` | The type of the feed attribute referenced in the attribute field mapping must match the type of the placeholder field. |
| ## `INVALID_CRITERION_FIELD` | The given criterion field does not exist. |
| ## `INVALID_CRITERION_TYPE` | The given criterion type does not exist. |
| ## `INVALID_PLACEHOLDER_FIELD` | The given placeholder field does not exist. |
| ## `INVALID_PLACEHOLDER_TYPE` | The given placeholder type does not exist. |
| ## `INVALID_PLACEHOLDER_TYPE_FOR_NON_SYSTEM_GENERATED_FEED` | The given placeholder type can only be mapped to system generated feeds. |
| ## `INVALID_PLACEHOLDER_TYPE_FOR_SYSTEM_GENERATED_FEED_TYPE` | The given placeholder type cannot be mapped to a system generated feed with the given type. |
| ## `LEGACY_FEED_TYPE_READ_ONLY` | Feed is read only. |
| ## `LOCATION_PLACEHOLDER_ONLY_FOR_PLACES_FEEDS` | Location placeholder feed mappings can only be created for Places feeds. |
| ## `MULTIPLE_MAPPINGS_FOR_CRITERION_FIELD` | Only one feed attribute mapping for a criterion field is allowed (depending on the criterion type). |
| ## `MULTIPLE_MAPPINGS_FOR_CRITERION_TYPE` | Only one feed mapping for a criterion type is allowed per customer. |
| ## `MULTIPLE_MAPPINGS_FOR_PLACEHOLDER_FIELD` | Only one feed attribute mapping for a placeholder field is allowed (depending on the placeholder type). |
| ## `MULTIPLE_MAPPINGS_FOR_PLACEHOLDER_TYPE` | Only one feed mapping for a placeholder type is allowed per feed or customer (depending on the placeholder type). |
| ## `NO_ATTRIBUTE_FIELD_MAPPINGS` | A feed mapping must contain at least one attribute field mapping. |
| ## `UNEXPECTED_ATTRIBUTE_FIELD_MAPPINGS` | This feed mapping may not contain any explicit attribute field mappings. |
| ## `UNKNOWN` | The received error code is not known in this version. |
| ## `UNSPECIFIED` | Enum unspecified. |