The code snippets are excerpts (or slightly simplififed ones) from Example_Clean_Hippo_Mirror_Docbase_Values_Having_Paths.
When a document contains mirror link nodes to other documents,
the mirror links nodes have hippo:docbase string property containing
a UUID of the referenced document handle node.
As explained in Tutorial: Exporting Document Content, the UUIDs might have been replaced by the node paths of the referenced document handle nodes during exporting process.
In this case, you can create a simple Groovy Updater script like explained in this page to update the docbase node paths by docbase UUIDs.
You can use JCR query like the following example in a Groovy Updater script to select
all the mirror nodes having a path (e.g, /content/documents/...) in hippo:docbase property instead of UUID.
//element(*)[jcr:like(@hippo:docbase,'/content/%')]
// 1. Read the current hippo:docbase property value.
def docbasePath = node.getProperty("hippo:docbase").getString()
// 2. If the hippo:docbase property value starts with '/' and there exists a node at the path,
// then replace the path by UUID.
if (StringUtils.startsWith(docbasePath, "/") && node.session.nodeExists(docbasePath)) {
def docbase = node.session.getNode(docbasePath).getIdentifier()
node.setProperty("hippo:docbase", docbase)
}