Add note about old git-lfs client for Geo requests

doc/administration/geo/index.md

@@ -116,6 +116,7 @@ The following are required to run Geo:
   - [Ubuntu](https://ubuntu.com) 16.04+
 - PostgreSQL 11+ with [Streaming Replication](https://wiki.postgresql.org/wiki/Streaming_Replication)
 - Git 2.9+
+- Git-lfs 2.4.2+ on the user side when using LFS
 - All nodes must run the same GitLab version.
 
 Additionally, check GitLab's [minimum requirements](../../install/requirements.md),

doc/administration/geo/replication/troubleshooting.md

@@ -782,3 +782,13 @@ To resolve this issue:
   using IPv6 to send its status to the **primary** node. If it is, add an entry to
   the **primary** node using IPv4 in the `/etc/hosts` file. Alternatively, you should
   [enable IPv6 on the **primary** node](https://docs.gitlab.com/omnibus/settings/nginx.html#setting-the-nginx-listen-address-or-addresses).
+
+## Fixing client errors
+
+### Authorization errors from LFS HTTP(s) client requests
+
+You may have problems if you're running a version of [Git LFS](https://git-lfs.github.com/) before 2.4.2.
+As noted in [this authentication issue](https://github.com/git-lfs/git-lfs/issues/3025),
+requests redirected from the secondary to the primary node do not properly send the
+Authorization header. This may result in either an infinite `Authorization <-> Redirect`
+loop, or Authorization errors.