# Problem after migration to H2

## post by rafal.kedziorski on Aug 28, 2024

Hi,

after migration to H2 (which makes no fun) I have now next problem

```auto
==> nexus.log <==
2024-08-28 14:02:14,255+0000 WARN  [qtp95736789-1369]  *UNKNOWN org.sonatype.nexus.transaction.RetryController - Exceeded retry limit: 8/8 (org.sonatype.nexus.datastore.api.DuplicateKeyException: Duplicate key)
2024-08-28 14:02:14,256+0000 WARN  [qtp95736789-1369]  *UNKNOWN org.sonatype.nexus.repository.httpbridge.internal.ViewServlet - Failure servicing: GET /repository/maven-public/org/apache/maven/plugins/maven-surefire-plugin/3.5.0/maven-surefire-plugin-3.5.0.pom
org.sonatype.nexus.datastore.api.DuplicateKeyException: Duplicate key
        at org.sonatype.nexus.datastore.mybatis.EntityExecutor.mapException(EntityExecutor.java:255)
        at org.sonatype.nexus.datastore.mybatis.EntityExecutor.update(EntityExecutor.java:77)
        at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:197)
        at org.sonatype.nexus.datastore.mybatis.DataAccessSqlSession.update(DataAccessSqlSession.java:83)
        at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:184)
        ... 226 common frames omitted
```

Best Regards,

Rafal

## post by rafal.kedziorski on Aug 28, 2024

And when I check this, I see:

What I did? I compiled same code with the new dependency on 6 computers in parallel. Looks like there is an threading problem in nexus. I’m using: 3.71.0-06

## post by rafal.kedziorski on Aug 28, 2024

OK, I restored my last backup after the migration and I started the compile process only on one computer. And I get the same error.

## post by rafal.kedziorski on Aug 28, 2024

Now I’m back to 3.70.1-02 with OrientDB and it works fine. And I’m very disappointed about the migration process.

## post by rafal.kedziorski on Aug 30, 2024

On GitHub is an Issue for this.

## post by rafal.kedziorski on Aug 30, 2024

The problem was reported 3 weeks ago and there is no warning on the migrations page. Why not?