DSpace 7 - No suggestions when adding a new metadata field to an existing item - solr

Question

In DSpace 7.4, while adding new metadata to an existing item I'm not getting any suggestions in the input box, is there any configuration step I'm missing?
I can see it working in the official demo site
here
I see in dspace.log that there is this API call when I type something in the input box:
GET /server/api/core/metadatafields/search/byFieldName
so I tried this with no results:
/server/#api/core/metadatafields/search/byFieldName?query=author
The same API call in the DSpace 7 demo site returns 3 results: https://api7.dspace.org/server/#api/core/metadatafields/search/byFieldName?query=author
Also, in solr.log I see this call, which returns no hits:
2023-01-11 13:09:55.709 INFO (qtp359742806-22) [ x:search] o.a.s.c.S.Request [search] webapp=/solr path=/select params={q=*:*&fl=search.resourcetype,search.resourceid,search.uniqueid,database_status&start=0&fq=fieldName_keyword:author*&fq=&wt=javabin&version=2} hits=0 status=0 QTime=1
Maybe there is a problem with SOLR?

Answer 1

Since it seemed to be a SOLR problem, I tried to reindex like this: dspace index-discovery -b, thus getting this error:
java.lang.NullPointerException: Cannot invoke "org.dspace.eperson.EPerson.getID()" because the return value of "org.dspace.authorize.ResourcePolicy.getEPerson()" is null
at org.dspace.discovery.SolrServiceResourceRestrictionPlugin.additionalIndex(SolrServiceResourceRestrictionPlugin.java:95)
at org.dspace.discovery.indexobject.IndexFactoryImpl.buildDocument(IndexFactoryImpl.java:67)
at org.dspace.discovery.indexobject.InprogressSubmissionIndexFactoryImpl.buildDocument(InprogressSubmissionIndexFactoryImpl.java:46)
at org.dspace.discovery.indexobject.WorkspaceItemIndexFactoryImpl.buildDocument(WorkspaceItemIndexFactoryImpl.java:63)
at org.dspace.discovery.indexobject.WorkspaceItemIndexFactoryImpl.buildDocument(WorkspaceItemIndexFactoryImpl.java:30)
at org.dspace.discovery.SolrServiceImpl.update(SolrServiceImpl.java:165)
at org.dspace.discovery.SolrServiceImpl.indexContent(SolrServiceImpl.java:155)
at org.dspace.discovery.SolrServiceImpl.updateIndex(SolrServiceImpl.java:340)
at org.dspace.discovery.SolrServiceImpl.updateIndex(SolrServiceImpl.java:327)
at org.dspace.discovery.IndexClient.internalRun(IndexClient.java:130)
at org.dspace.scripts.DSpaceRunnable.run(DSpaceRunnable.java:104)
at org.dspace.app.launcher.ScriptLauncher.executeScript(ScriptLauncher.java:149)
at org.dspace.app.launcher.ScriptLauncher.handleScript(ScriptLauncher.java:131)
at org.dspace.app.launcher.ScriptLauncher.main(ScriptLauncher.java:98)
And found the solution here: https://groups.google.com/g/dspace-tech/c/ioukme4el9o.
WARNING: It's recommended to test this in a development environment first.
The problem is that there was several rows with no eperson_id and no epersongroup_id in the resourcepolicy table. So, I've deleted those rows with delete from resourcepolicy where eperson_id is null and epersongroup_id is null; and reindexed: dspace index-discovery -b.
Note: this problem seems to occur whenever the database comes from a dump of a previous DSpace version. In my case I restored a dump from a 5.6 version and migrated it to 7.4 before running into this issue.