Association errors with Doctrine after upgrade - doctrine-orm

Question

I'm working on upgrading a product from Symfony 2.7 to 4.2 (currently at 3.4) and am getting stuck with some existing associations.
The field AppBundle\Entity\User#currentBillingAgreement is on the owning side of a bi-directional relationship, but the specified mappedBy association on the target-entity AppBundle\Entity\BillingAgreement# does not contain the required 'inversedBy' attribute.
If association AppBundle\Entity\User#currentBillingAgreement is one-to-one, then the inversed side AppBundle\Entity\BillingAgreement#user has to be one-to-one as well.
The User entity has these associations:
/**
* #var BillingAgreement
* #ORM\OneToOne(
* targetEntity="AppBundle\Entity\BillingAgreement",
* inversedBy="user",
* cascade={"persist"}
* )
* #ORM\JoinColumn(
* name="currentBillingAgreementID",
* referencedColumnName="billingAgreementID"
* )
*/
protected $currentBillingAgreement;
/**
* #var ArrayCollection
* #ORM\OneToMany(
* targetEntity="AppBundle\Entity\BillingAgreement",
* mappedBy="user",
* cascade={"persist"}
* )
* #Serializer\Exclude()
*/
protected $billingAgreements;
and BillingAgreement has this:
/**
* #var User
* #ORM\ManyToOne(
* targetEntity="AppBundle\Entity\User",
* inversedBy="billingAgreements"
* )
* #ORM\JoinColumn(
* name="userID",
* referencedColumnName="userID",
* nullable=false
* )
*/
protected $user;
When I add a OneToOne mapping to BillingAgreement::$user (#ORM\OneToOne(targetEntity="AppBundle\Entity\User", inversedBy="currentBillingAgreement")), I get a new error:
The field AppBundle\Entity\BillingAgreement#user is on the owning side of a bi-directional relationship, but the specified mappedBy association on the target-entity AppBundle\Entity\User# does not contain the required 'inversedBy' attribute.
and the original 2 errors remain.

Answer 1

You can make the OneToOne association unidirectional by removing inversedBy="user", from the annotation.
or
Use a different field for each association on BillingAgreement entity:
/**
* #var User
* #ORM\ManyToOne(
* targetEntity="AppBundle\Entity\User",
* inversedBy="billingAgreements"
* )
* #ORM\JoinColumn(
* name="userID",
* referencedColumnName="userID",
* nullable=false
* )
*/
protected $user;
/**
* #var User
* #ORM\OneToOne(targetEntity="AppBundle\Entity\User", inversedBy="currentBillingAgreement")
*/
protected $singleUser;
and in User entity:
/**
* #var BillingAgreement
* #ORM\OneToOne(
* targetEntity="AppBundle\Entity\BillingAgreement",
* inversedBy="singleUser",
* cascade={"persist"}
* )
* #ORM\JoinColumn(
* name="currentBillingAgreementID",
* referencedColumnName="billingAgreementID"
* )
*/
protected $currentBillingAgreement;
/**
* #var ArrayCollection
* #ORM\OneToMany(
* targetEntity="AppBundle\Entity\BillingAgreement",
* mappedBy="user",
* cascade={"persist"}
* )
* #Serializer\Exclude()
*/
protected $billingAgreements;
References
Doctrine 2.6 Association Mapping