[Yandex Cloud documentation](../../index.md) > [Yandex MetaData Hub](../index.md) > Troubleshooting

# Troubleshooting in Yandex MetaData Hub

This section describes issues you may encounter in the service and how to troubleshoot them.

* [Apache Hive™ Metastore](#metastore)
* [Yandex Schema Registry](#schema-registry-full-name)

## Troubleshooting in Apache Hive™ Metastore {#metastore}

### Error when creating a database in Apache Hive™ Metastore {#create-db-in-hive}

The error occurs if you use the following syntax to create a database:

```sql
CREATE DATABASE IF NOT EXISTS <DB_name>;
```

**Solution**
Apache Hive™ Metastore does not allow creating a database or table in Hive: they are stored in a [Yandex Object Storage bucket](../../storage/concepts/bucket.md) linked to a Yandex Data Processing cluster. To create a database, use the following syntax:

```sql
CREATE DATABASE IF NOT EXISTS <DB_name> LOCATION <DB_location>;
```

In the `LOCATION` parameter, specify the path to the bucket and the database in it in the following format: `s3a://<bucket_name>/<folder_name>/<DB_name>`. Specifying a folder is optional; however, objects will load into a folder faster than into the bucket root.

### No permission error when attaching a service account to the cluster {#attach-service-account}

#### How can I fix the no permission error when connecting a service account to the cluster? {#attach-service-account}

Error message:

```text
ERROR: rpc error: code = PermissionDenied desc = you do not have permission to access the requested service account or service account does not exist
```

This error occurs if you link a service account to a cluster while creating or modifying it.

**Solution**
[Assign](../../iam/operations/roles/grant.md) the [iam.serviceAccounts.user](../../iam/security/index.md#iam-serviceAccounts-user) role or higher to your Yandex Cloud account.

## Troubleshooting in Yandex Schema Registry {#schema-registry-full-name}

### Error when adding or deleting optional parameters {#avoid-errors-while-evolving-schema}

If a `Confluent` [compatibility check policy](../concepts/compatibility-check-policy.md) is configured at the namespace level, the following errors may occur when adding or deleting optional parameters in the schema:

* `PROPERTY_ADDED_TO_OPEN_CONTENT_MODEL`
* `PROPERTY_REMOVED_FROM_CLOSED_CONTENT_MODEL`

**Solution**
The `Confluent` compatibility check policy is based on the Confluent Schema Registry standards and implements mathematically accurate compatibility checks. This policy does not allow adding or removing optional parameters in `object` fields, causing the errors mentioned above.

To add or delete optional parameters, select the `optional-friendly` JSON compatibility check policy in the [namespace](../operations/update-name-space.md). It is based on [using various content models](../concepts/schema-registry-content-model.md#optional-parameters-compatibility-solution) for the producer and the consumer, where only the producer schema is registered. The compatibility check involves converting the consumer schema from an open content model to a closed one and comparing it with the registered producer schemas. This enables you to add or remove optional parameters while maintaining full transitive compatibility.

_Apache® and [Apache Hive™](https://hive.apache.org/) are either registered trademarks or trademarks of the Apache Software Foundation in the United States and/or other countries._