JSON error when attempting to sync users from federation

Getting advice
1

I’m trying to migrate a Keycloak setup to Quarkus (26.1.4), but I’m having trouble migrating the data from the old system. I first tried to do a full export through CLI and importing it into the new server, but that is taking around 5 days in total, which would be too much downtime. As a workaround I am now trying to export the realm without the users (-Dkeycloak.migration.usersExportStrategy=SKIP and importing them from LDAP in the Quarkus Keycloak. The export and import works well and fast enough, but when I try to sync the LDAP users (User federation → Action → Sync all users) it freezes for a while and gives the error “Could not sync users: ‘’”, without giving a reason why (also in the logs):

sync

I also noticed that when I go to “Users” afterwards, I get the following error:

No users found due to Expected ‘:’ after property name in JSON at position 8187 (line 1 column 8188)

And when searching for * in Users:

No users found, could be due to wrongly configured federated provider Expected ‘:’ after property name in JSON at position 8187 (line 1 column 8188)

The “Test connection” and “Test authentication” both work in the Users federation settings.
Does anyone know what could be the cause of this or which JSON is meant by the error?

2

Look on your server log/output to get more information. There‘s „something“ wrong in your configuration/communication.

3

Did you validate the JSON format of your transferred data? This somehow also seems to be a malformed JSON object that is being communicated during sync. Maybe try to use notepad++ or some other local tool to simply verify your JSON structure.