Pimcore\Model\DataObject\ClassDefinition\Helper\LinkGeneratorResolver::resolveGenerator(): Argument #1 must be of type string, null given

[olifrieda]

See:
https://github.com/pimcore/pimcore/blob/ea8a33692ad3a2c42cd407af0e9654492e529f9e/models/DataObject/ClassDefinition.php#L934

Explanation:
$this->getLinkGeneratorReference() may return string or null, DataObject\ClassDefinition\Helper\LinkGeneratorResolver::resolveGenerator() only accepts string.

How to reproduce:
Create data object with Link, but do not set link value. Open data object.

Error:

Pimcore\Model\DataObject\ClassDefinition\Helper\LinkGeneratorResolver::resolveGenerator(): Argument pimcore/pimcore#1 ($generatorClass) must be of type string, null given, called in /var/www/html/vendor/pimcore/pimcore/models/DataObject/ClassDefinition.php on line 934

How to fix:

    public function getLinkGenerator(): ?ClassDefinition\LinkGeneratorInterface
    {
        $reference = $this->getLinkGeneratorReference();
        if ($reference === null) {
            return null;
        }

        return DataObject\ClassDefinition\Helper\LinkGeneratorResolver::resolveGenerator($reference);
    }

Affected version: 2026.2