Uninstalling mod packs and fix packs

After installing a mod pack or fix pack, you can revert to a previous fix pack or the GA level of the Db2® database product.

On Linux® and UNIX operating systems, you can go back to an earlier fix pack or the GA level.

On Windows operating systems, you cannot go back to a previous fix pack or the GA level unless you uninstall the current fix pack, then install the previous level.

Procedure

Follow these steps if the mod pack or fix pack overwrote the original installation location:

On Linux or UNIX operating systems, to uninstall a mod pack or fix pack, use the installFixPack command with the force option (-f) to bypass the level check. The command must be run from the lower level mod pack, fix pack, or GA image. For example:
```
./installFixPack -f level -b DB2DIR
```
where
- DB2DIR is the location of the Db2 database product that you want to force to a lower level mod pack, fix pack, or GA image. For example:
```
./installFixPack -f level -b /opt/ibm/db2/V11.5
```
On Windows operating system, to uninstall a mod pack or fix pack, use the Add/Remove Programs window, accessible through the Windows Control Panel. Refer to your operating system's help for more information about removing software products from your Windows operating system.
Associate the instance with another Db2 copy that is at a lower level than the original Db2 copy where the instance was running. You can update all instances by issuing db2iupdt -f level from the new directory.

Follow this step if the mod pack or fix pack is installed on a separate directory:

On Linux or UNIX operating systems, to uninstall a mod pack or fix pack, use the db2iupdt command with the force option (-f) to bypass the level check. For example:
```
DB2DIR/instance/db2iupdt -f level instanceName
```
Where DB2DIR is in the previous mod pack or fix pack location.

Notes:

Before you uninstall the current mod pack or fix pack, remove or uninstall any functionality that does not apply to the earlier mod pack, fix pack, or the GA level. After you uninstall the mod pack/fix pack, static packages must be rebound. If you ran db2updv115 on the current level, you need to run db2dupv115 -a after moving to a lower level.
If the current mod pack or fix pack includes fallback-incompatible features and you have explicitly enabled any of them via a registry variable, you will need to restore the database from the backup taken before the mod pack or fix pack was installed.

Rolling back from Db2 11.5.5

If a user is granted any of the new schema privileges/authorities and the Db2 instance is rolled back from 11.5.5 to an older mod pack, the user still holds them after the rollback and these authorities need to be revoked manually.

The DB2_ENABLE_SCHEMA_AUTHORIZATION registry variable needs to be set to YES and then, for each row in the SYSCAT.SCHEMAAUTH catalog view, an associated revoke statement needs to be issued.

For example, if a user named BOSS holds SELECTIN privilege on a schema named TEST, the revoke statement would look like the following.

REVOKE SELECTIN ON SCHEMA TEST FROM USER BOSS

Once the new schema privileges/authorities that were previously granted have been revoked, the DB2_ENABLE_SCHEMA_AUTHORIZATION registry variable can be set back to NO.

Note: Even in Db211.5.5, where the new schema privileges and authorities are enabled by default, none of them are granted implicitly. For example, no new schema privileges or authorities are granted implicitly during object creation.