Possible NullPointerException when retrying a failed filesystem migration from 10.11

I just upgraded from 10.11 to 11.0 with apt-get upgrade, as always, and after restarting Tomcat, whenever I try to enter a wiki and it starts to init, I get tons of exceptions in the logfile like this:

2019-01-29 19:58:23,803 [XWiki initialization] INFO .HibernateDataMigrationManager - The following data migration(s) will be applied for wiki [xxxxxx] currently in version [1008010]:
2019-01-29 19:58:23,803 [XWiki initialization] INFO .HibernateDataMigrationManager - R1100000XWIKI15620 - Move the store to a new location. Change the path from URL encoding to hash based to support long references.
2019-01-29 19:58:23,803 [XWiki initialization] INFO .HibernateDataMigrationManager - Checking Hibernate mapping and updating schema if needed for wiki [xxxxxx]
2019-01-29 19:58:24,037 [XWiki initialization] INFO .HibernateDataMigrationManager - Starting data migration [R1100000XWIKI15620] with version [1100000] on database [xxxxxx]
2019-01-29 19:58:24,051 [XWiki initialization] ERROR .HibernateDataMigrationManager - Failed to migrate database [xxxxxx]...
com.xpn.xwiki.store.migration.DataMigrationException: Data migration R1100000XWIKI15620 failed
at com.xpn.xwiki.store.migration.hibernate.AbstractHibernateDataMigration.migrate(AbstractHibernateDataMigration.java:120)
at com.xpn.xwiki.store.migration.AbstractDataMigrationManager.startMigrations(AbstractDataMigrationManager.java:848)
at com.xpn.xwiki.store.migration.AbstractDataMigrationManager.migrateDatabase(AbstractDataMigrationManager.java:743)
at com.xpn.xwiki.store.migration.AbstractDataMigrationManager.startMigrations(AbstractDataMigrationManager.java:674)
at com.xpn.xwiki.store.migration.hibernate.HibernateDataMigrationManager.startMigrations(HibernateDataMigrationManager.java:346)
at com.xpn.xwiki.store.migration.AbstractDataMigrationManager.startMigrationsOnlyOnce(AbstractDataMigrationManager.java:644)
at com.xpn.xwiki.store.migration.AbstractDataMigrationManager.tryToProcceedToMigration(AbstractDataMigrationManager.java:621)
at com.xpn.xwiki.store.migration.AbstractDataMigrationManager.checkDatabase(AbstractDataMigrationManager.java:538)
at com.xpn.xwiki.internal.store.hibernate.HibernateStore.setWiki(HibernateStore.java:339)
at com.xpn.xwiki.internal.store.hibernate.HibernateStore.setWiki(HibernateStore.java:302)
at com.xpn.xwiki.internal.store.hibernate.HibernateStore.beginTransaction(HibernateStore.java:472)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.beginTransaction(XWikiHibernateBaseStore.java:682)
at com.xpn.xwiki.store.XWikiHibernateStore.loadXWikiDoc(XWikiHibernateStore.java:894)
at com.xpn.xwiki.store.XWikiCacheStore.loadXWikiDoc(XWikiCacheStore.java:353)
at com.xpn.xwiki.XWiki.getDocument(XWiki.java:1916)
at com.xpn.xwiki.XWiki.getDocument(XWiki.java:1978)
at com.xpn.xwiki.XWiki.initializeMandatoryDocument(XWiki.java:1333)
at com.xpn.xwiki.XWiki.initializeMandatoryDocuments(XWiki.java:1307)
at com.xpn.xwiki.XWiki.initXWiki(XWiki.java:1225)
at com.xpn.xwiki.XWiki.initXWiki(XWiki.java:1167)
at com.xpn.xwiki.XWiki.<init>(XWiki.java:1140)
at com.xpn.xwiki.internal.XWikiInitializerJob.runInternal(XWikiInitializerJob.java:117)
at org.xwiki.job.AbstractJob.runInContext(AbstractJob.java:236)
at org.xwiki.job.AbstractJob.run(AbstractJob.java:213)
at java.lang.Thread.run(Thread.java:748)
Caused by: com.xpn.xwiki.XWikiException: Error number 0 in 3: Exception while hibernate execute
at com.xpn.xwiki.store.XWikiHibernateBaseStore.execute(XWikiHibernateBaseStore.java:927)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.executeWrite(XWikiHibernateBaseStore.java:1036)
at org.xwiki.store.filesystem.internal.migration.R1100000XWIKI15620DataMigration.hibernateMigrate(R1100000XWIKI15620DataMigration.java:121)
at com.xpn.xwiki.store.migration.hibernate.AbstractHibernateDataMigration.migrate(AbstractHibernateDataMigration.java:118)
... 24 common frames omitted
Caused by: org.hibernate.HibernateException: Failed to refactor filesystem store paths
at org.xwiki.store.filesystem.internal.migration.R1100000XWIKI15620DataMigration.lambda$hibernateMigrate$0(R1100000XWIKI15620DataMigration.java:125)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.execute(XWikiHibernateBaseStore.java:921)
... 27 common frames omitted
Caused by: java.lang.NullPointerException: null
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:105)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:108)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:108)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:108)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:108)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:108)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:108)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:108)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11EntityReference(AbstractFileStoreDataMigration.java:108)
at org.xwiki.store.filesystem.internal.migration.AbstractFileStoreDataMigration.getPre11DocumentReference(AbstractFileStoreDataMigration.java:116)
at org.xwiki.store.filesystem.internal.migration.R1100000XWIKI15620DataMigration.migrateDocumentContent(R1100000XWIKI15620DataMigration.java:167)
at org.xwiki.store.filesystem.internal.migration.R1100000XWIKI15620DataMigration.migrate(R1100000XWIKI15620DataMigration.java:152)
at org.xwiki.store.filesystem.internal.migration.R1100000XWIKI15620DataMigration.migrate(R1100000XWIKI15620DataMigration.java:154)
at org.xwiki.store.filesystem.internal.migration.R1100000XWIKI15620DataMigration.migrate(R1100000XWIKI15620DataMigration.java:154)
at org.xwiki.store.filesystem.internal.migration.R1100000XWIKI15620DataMigration.lambda$hibernateMigrate$0(R1100000XWIKI15620DataMigration.java:123)
... 28 common frames omitted

And, therefore, I cannot enter XWiki.

I'm on Ubuntu 16.04 with MySQL 5.7 and also using LDAP, I can provide with any other information required.

See also https://forum.xwiki.org/t/attachment-issues-after-upgrade-from-10-11-to-11-0.