I have tried to upgrade my Symfony example project https://github.com/hantsy/symfony-rest-sample to v8.0, there is a test failed due to error like this.

https://github.com/hantsy/symfony-rest-sample/actions/runs/19756748559/job/56609665804#step:11:29

{"error":"A circular reference has been detected when serializing the object of 
class \u0022App\\Entity\\Comment\u0022 (configured limit: 1)."}

The Post and Comment entity is a one-to-many relation, and I set the relation on both side.

But on the Comment, I added a [Ignore] to avoid serialization on post field.

#[Entity(repositoryClass: CommentRepository::class)]
class Comment
{
    // ...

    #[ManyToOne(targetEntity: "Post", inversedBy: "comments")]
    #[JoinColumn(name: "post_id", referencedColumnName: "id")]
    #[Ignore]
    private Post $post;

The codes worked since Symfony v5.x - 7.3, but failed when upgrading v8.0.