Document pre-13.8 preflight check bug

doc/administration/geo/disaster_recovery/index.md

@@ -145,6 +145,13 @@ Note the following when promoting a secondary:
    a point-in-time recovery to the last known state.
    Data that was created on the primary while the secondary was paused will be lost.
 
+   NOTE:
+   In GitLab 13.7 and earlier, if you have a data type with zero items to sync,
+   this command reports `ERROR - Replication is not up-to-date` even if
+   replication is actually up-to-date. If replication and verification output
+   shows that it is complete, you can add `--skip-preflight-checks` to make the
+   command complete promotion. This bug was fixed in GitLab 13.8 and later.
+
    To promote the secondary node to primary along with preflight checks:
 
    ```shell

doc/administration/geo/disaster_recovery/planned_failover.md

@@ -45,6 +45,12 @@ be found in `/var/opt/gitlab/gitlab-rails/shared/pages` if using Omnibus).
 
 ## Preflight checks
 
+NOTE:
+In GitLab 13.7 and earlier, if you have a data type with zero items to sync,
+this command reports `ERROR - Replication is not up-to-date` even if
+replication is actually up-to-date. This bug was fixed in GitLab 13.8 and
+later.
+
 Run this command to list out all preflight checks and automatically check if replication and verification are complete before scheduling a planned failover to ensure the process will go smoothly:
 
 ```shell

doc/administration/geo/disaster_recovery/runbooks/planned_failover_single_node.md

@@ -233,12 +233,25 @@ To promote the secondary node:
    check if replication and verification are complete before scheduling a planned
    failover to ensure the process will go smoothly:
 
+   NOTE:
+   In GitLab 13.7 and earlier, if you have a data type with zero items to sync,
+   this command reports `ERROR - Replication is not up-to-date` even if
+   replication is actually up-to-date. This bug was fixed in GitLab 13.8 and
+   later.
+
    ```shell
    gitlab-ctl promotion-preflight-checks
    ```
 
 1. Promote the **secondary**:
 
+   NOTE:
+   In GitLab 13.7 and earlier, if you have a data type with zero items to sync,
+   this command reports `ERROR - Replication is not up-to-date` even if
+   replication is actually up-to-date. If replication and verification output
+   shows that it is complete, you can add `--skip-preflight-checks` to make the
+   command complete promotion. This bug was fixed in GitLab 13.8 and later.
+
    ```shell
    gitlab-ctl promote-to-primary-node
    ```

doc/administration/geo/replication/troubleshooting.md

@@ -678,6 +678,20 @@ sudo /opt/gitlab/embedded/bin/gitlab-pg-ctl promote
 
 GitLab 12.9 and later are [unaffected by this error](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/5147).
 
+### Message: `ERROR - Replication is not up-to-date` during `gitlab-ctl promotion-preflight-checks`
+
+In GitLab 13.7 and earlier, if you have a data type with zero items to sync,
+this command reports `ERROR - Replication is not up-to-date` even if
+replication is actually up-to-date. This bug was fixed in GitLab 13.8 and
+later.
+
+### Message: `ERROR - Replication is not up-to-date` during `gitlab-ctl promote-to-primary-node`
+
+In GitLab 13.7 and earlier, if you have a data type with zero items to sync,
+this command reports `ERROR - Replication is not up-to-date` even if
+replication is actually up-to-date. If replication and verification output
+shows that it is complete, you can add `--skip-preflight-checks` to make the command complete promotion. This bug was fixed in GitLab 13.8 and later.
+
 ## Expired artifacts
 
 If you notice for some reason there are more artifacts on the Geo