Error on OPML import

[asm0dey]

On version 1.5 with java 15, I've got the following error on OPML import:

SEVERE: Could not dispatch event: SubscriptionImportedEvent{user=User{id=fa63dcbf-3642-40f9-be03-ebd19cb0f33f, username=asm0dey}, importFile=/tmp/reader_opml_import15619541884854815570.tmp} to handler [wrapper public void com.sismics.reader.core.listener.async.SubscriptionImportAsyncListener.onSubscriptionImport(com.sismics.reader.core.event.SubscriptionImportedEvent) throws java.lang.Exception]
java.lang.reflect.InvocationTargetException
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:567)
        at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
        at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
        at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
        at com.google.common.eventbus.AsyncEventBus.access$001(AsyncEventBus.java:34)
        at com.google.common.eventbus.AsyncEventBus$1.run(AsyncEventBus.java:100)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: javax.persistence.RollbackException: Transaction marked as rollbackOnly
        at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:72)
        at com.sismics.reader.core.util.TransactionUtil.handle(TransactionUtil.java:74)
        at com.sismics.reader.core.listener.async.SubscriptionImportAsyncListener.onSubscriptionImport(SubscriptionImportAsyncListener.java:83)

It imports 3 feeds and then throws this exception.