# SQL Persistence Upgrade - Support NServiceBus 5 subscribers



## Summary

This guidance explains how to allow processing of subscription messages sent by endpoints using NServiceBus 5 and lower, as described in the issue [Subscription store does not accept subscribe requests issued from NServiceBus 5 and below](https://github.com/Particular/NServiceBus.Persistence.Sql/issues/112).

This issue makes it impossible for subscriber endpoints using NServiceBus versions 5 and lower to subscribe to events published by endpoints using NServiceBus versions 6 in combination with [SQL Persistence](/persistence/sql/index.md). The subscription messages are eventually moved to the error queue. This causes message loss as the subscriber never receives events it subscribed to.


## Compatibility

This issue has been resolved in the following patch versions of [SQL Persistence](/persistence/sql/index.md) as defined in the NServiceBus [support policy](/nservicebus/upgrades/support-policy.md):

 * [2.1.2](https://github.com/Particular/NServiceBus.Persistence.Sql/releases/tag/2.1.2)
 * [2.0.1](https://github.com/Particular/NServiceBus.Persistence.Sql/releases/tag/2.0.1)
 * [1.0.5](https://github.com/Particular/NServiceBus.Persistence.Sql/releases/tag/1.0.5)

If any of the supported affected minor versions (2.1.x, 2.0.x, or 1.0.x) are used, these should be updated to the latest patch release.


## Upgrade steps

Steps:

 * Update to latest patch release
 * Deploy the new version


## Updating database schema on Oracle Database

If using Oracle Database, update the database schema prior to running the above "Upgrade steps".

The schema created on Oracle Database does not allow `NULL` in the `ENDPOINT` column, and this patch requires that it does. The following script illustrates an example DDL statement for an endpoint named `Publisher`.

> [!NOTE]
> This procedure does not require any downtime. It is advisable to execute it when affected endpoint instances are not under heavy load.

> [!WARNING]
> Run this script on a testing or staging environment first to verify that it works as expected.

```sql
alter table PUBLISHER_SS modify ENDPOINT varchar2(200) null;
```