Merge pull request #296859 from ilijazagorac/patch-22

Update known-issues.md

Author: prmerger-automator[bot]

articles/synapse-analytics/known-issues.md

@@ -27,6 +27,7 @@ To learn more about Azure Synapse Analytics, see the [Azure Synapse Analytics Ov
 |Azure Synapse dedicated SQL pool|[Query failure when ingesting a parquet file into a table with AUTO_CREATE_TABLE='ON'](#query-failure-when-ingesting-a-parquet-file-into-a-table-with-auto_create_tableon)|Has workaround|
 |Azure Synapse dedicated SQL pool|[Queries failing with Data Exfiltration Error](#queries-failing-with-data-exfiltration-error)|Has workaround|
 |Azure Synapse dedicated SQL pool|[UPDATE STATISTICS statement fails with error: "The provided statistics stream is corrupt."](#update-statistics-failure)|Has workaround|
+|Azure Synapse dedicated SQL pool|[Enable TDE gateway time-outs in ARM deployment](#enable-tde-gateway-time-outs-in-arm-deployment)|Has workaround|
 |Azure Synapse serverless SQL pool|[Query failures from serverless SQL pool to Azure Cosmos DB analytical store](#query-failures-from-serverless-sql-pool-to-azure-cosmos-db-analytical-store)|Has workaround|
 |Azure Synapse serverless SQL pool|[Azure Cosmos DB analytical store view propagates wrong attributes in the column](#azure-cosmos-db-analytical-store-view-propagates-wrong-attributes-in-the-column)|Has workaround|
 |Azure Synapse serverless SQL pool|[Query failures in serverless SQL pools](#query-failures-in-serverless-sql-pools)|Has workaround|
@@ -84,6 +85,13 @@ When a new constraint is added to a table, a related statistic is created in the
 
 **Workaround**: Identify if a constraint and clustered index exist on the table. If so, DROP both the constraint and clustered index. After that, recreate the clustered index and then the constraint *ensuring that both include the same columns in the same order.* If the table does not have a constraint and clustered index, or if the above step results in the same error, contact the Microsoft Support Team for assistance.
 
+### Enable TDE gateway time-outs in ARM deployment 
+
+Updating TDE (Transparent data encryption) is internally implemented as a synchronous operation, subject to a time-out which can be exceeded. Although the time-out was exceeded, behind the scenes the TDE operation in most cases succeeds, but causes successor operations in the ARM template to be rejected.
+
+**Workaround**: There are two ways to mitigate this issue. The preferred option is to split the ARM template into multiple templates, so that one of the templates contains TDE update. That action reduces the chance of a time-out. 
+Other option is to retry the deployment after several minutes. During the wait time, the TDE update operation most likely will succeed and re-deploying the template the second time could execute previously rejected operations.
+
 ### Tag updates appear to fail
 
 When making a change to the [tags](../azure-resource-manager/management/tag-resources-portal.md) of a dedicated SQL pool through Azure portal or other methods, an error message can appear even though the change is made successfully.