add reindexing note

Author: mdbirnstiehl

solutions/observability/apps/upgrade-self-installation-of-apm-integration-to-8x.md

@@ -6,7 +6,7 @@ mapped_pages:
 
 
 
-# Upgrade a self-installation of the APM integration to 8.x [apm-upgrade-8.0-self-integration]
+# Upgrade a self-installation of the APM integration to 9.0 [apm-upgrade-9.0-self-integration]
 
 
 This upgrade guide is for the Elastic APM integration. Only use this guide if both of the following are true:
@@ -34,3 +34,5 @@ This upgrade guide is for the Elastic APM integration. Only use this guide if bo
     3. Choose **Upgrade agent** from the **Actions** menu next to the agent you want to upgrade. The **Upgrade agent** option is grayed out when an upgrade is unavailable, or the {{kib}} version is lower than the agent version.
 
     For more details, or for bulk upgrade instructions, see [Upgrade {{agent}}](/reference/fleet/upgrade-elastic-agent.md)
+
+3. When upgrading from 7.x to 9.0 if you reindex 7.x indices, you need to either add [ILM privileges](https://www.elastic.co/guide/en/apm/guide/7.17/privileges-to-setup-beats.html#_set_up_ilm) for `reindexed-v*-apm*` indices or set the indices to `readonly`.

solutions/observability/apps/upgrade-self-installation-of-apm-server-standalone-to-8x.md

@@ -25,6 +25,7 @@ This upgrade guide is for the standalone method of running APM Server. Only use
 2. Review the [Elastic APM release notes](apm-server://release-notes/index.md) and [Elastic {{observability}} release notes](/release-notes/elastic-observability/release-notes.md).
 
 
+
 ## Upgrade steps [_upgrade_steps]
 
 1. **Upgrade the {{stack}} to version 9.0**
@@ -49,6 +50,8 @@ This upgrade guide is for the standalone method of running APM Server. Only use
 
     Additional details are available in [start the APM Server](apm-server-binary.md#apm-server-starting).
 
-5. **(Optional) Upgrade to the APM integration**
+5. When upgrading from 7.x to 9.0 if you reindex 7.x indices, you need to either add [ILM privileges](https://www.elastic.co/guide/en/apm/guide/7.17/privileges-to-setup-beats.html#_set_up_ilm) for `reindexed-v*-apm*` indices or set the indices to `readonly`.
+
+6. **(Optional) Upgrade to the APM integration**
 
     Got time for one more upgrade? See [Switch to the Elastic APM integration](switch-to-elastic-apm-integration.md).