> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hedera.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ConsensusUpdateTopic

All fields left null will not be updated.

## ConsensusUpdateTopicTransactionBody

| Field              | Type                                                     | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |
| ------------------ | -------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | - |
| `topicID`          | [TopicID](/reference/protobuf/basic-types/topicid)       | UNDOCUMENTED                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| `memo`             | google.protobuf.StringValue                              | Short publicly visible memo about the topic. No guarantee of uniqueness. Null for "do not update".                                                                                                                                                                                                                                                                                                                                                                                        |   |
| `expirationTime`   | [Timestamp](/reference/protobuf/miscellaneous/timestamp) | <p>Effective consensus timestamp at (and after) which all consensus transactions and queries will fail.<br />The expirationTime may be no longer than MAX\_AUTORENEW\_PERIOD (8000001 seconds) from the consensus timestamp of<br />this transaction.<br />On topics with no adminKey, extending the expirationTime is the only updateTopic option allowed on the topic.<br />If unspecified, no change.</p>                                                                              |   |
| `adminKey`         | [Key](/reference/protobuf/basic-types/key)               | <p>Access control for update/delete of the topic.<br />If unspecified, no change.<br />If empty keyList - the adminKey is cleared.</p>                                                                                                                                                                                                                                                                                                                                                    |   |
| `submitKey`        | [Key](/reference/protobuf/basic-types/key)               | <p>Access control for ConsensusService.submitMessage.<br />If unspecified, no change.<br />If empty keyList - the submitKey is cleared.</p>                                                                                                                                                                                                                                                                                                                                               |   |
| `autoRenewPeriod`  | [Duration](/reference/protobuf/miscellaneous/duration)   | <p>The amount of time to extend the topic's lifetime automatically at expirationTime if the autoRenewAccount is<br />configured and has funds (once autoRenew functionality is supported by HAPI).<br />Limited to between MIN\_AUTORENEW\_PERIOD (6999999 seconds) and MAX\_AUTORENEW\_PERIOD (8000001 seconds) by<br />servers-side configuration (which may change).<br />If unspecified, no change.</p>                                                                               |   |
| `autoRenewAccount` | [AccountID](/reference/protobuf/basic-types/accountid)   | <p>Optional account to be used at the topic's expirationTime to extend the life of the topic.<br />Once autoRenew functionality is supported by HAPI, the topic lifetime will be extended up to a maximum of the<br />autoRenewPeriod or however long the topic can be extended using all funds on the account (whichever is the<br />smaller duration/amount).<br />If specified as the default value (0.0.0), the autoRenewAccount will be removed.<br />If unspecified, no change.</p> |   |
| `memo`             | string                                                   | The memo associated with the topic (UTF-8 encoding max 100 bytes)                                                                                                                                                                                                                                                                                                                                                                                                                         |   |