When importing artifact, I've got the following fatal error:

PHP Fatal error: Call to a member function isProjectAllowedToUseNature() on a non-object in /usr/share/tuleap/plugins/tracker/include/Tracker/FormElement/Tracker_FormElement_Field_ArtifactLink.class.php on line 1375
PHP Stack trace:
PHP 1. {main}() /usr/share/tuleap/src/utils/import_project_xml.php:0
PHP 2. ProjectXMLImporter->importFromArchive() /usr/share/tuleap/src/utils/import_project_xml.php:150
PHP 3. ProjectXMLImporter->importContent() /usr/share/tuleap/src/common/project/ProjectXMLImporter.class.php:108
PHP 4. EventManager->processEvent() /usr/share/tuleap/src/common/project/ProjectXMLImporter.class.php:148
PHP 5. EventManager->processEventOnListener() /usr/share/tuleap/src/common/event/EventManager.class.php:77
PHP 6. PluginProxy->processEvent() /usr/share/tuleap/src/common/event/EventManager.class.php:91
PHP 7. trackerPlugin->import_xml_project() /usr/share/tuleap/src/common/plugin/PluginProxy.php:57
PHP 8. TrackerXmlImport->import() /usr/share/tuleap/plugins/tracker/include/trackerPlugin.class.php:789
PHP 9. TrackerXmlImport->importChangesets() /usr/share/tuleap/plugins/tracker/include/TrackerXmlImport.class.php:227
PHP 10. Tracker_Artifact_XMLImport->importArtifactChangesFromXML() /usr/share/tuleap/plugins/tracker/include/TrackerXmlImport.class.php:316
PHP 11. Tracker_Artifact_XMLImport->importChangesets() /usr/share/tuleap/plugins/tracker/include/Tracker/Artifact/XMLImport.class.php:180
PHP 12. Tracker_Artifact_XMLImport->importAllChangesetsBySubmitionDate() /usr/share/tuleap/plugins/tracker/include/Tracker/Artifact/XMLImport.class.php:270
PHP 13. Tracker_Artifact_XMLImport->importRemainingChangeset() /usr/share/tuleap/plugins/tracker/include/Tracker/Artifact/XMLImport.class.php:317
PHP 14. Tracker_Artifact_XMLImport_ArtifactFieldsDataBuilder->getFieldsData() /usr/share/tuleap/plugins/tracker/include/Tracker/Artifact/XMLImport.class.php:378
PHP 15. Tracker_Artifact_XMLImport_ArtifactFieldsDataBuilder->appendValidValue() /usr/share/tuleap/plugins/tracker/include/Tracker/Artifact/XMLImport/ArtifactFieldsDataBuilder.class.php:114
PHP 16. Tracker_FormElement_Field->validateField() /usr/share/tuleap/plugins/tracker/include/Tracker/Artifact/XMLImport/ArtifactFieldsDataBuilder.class.php:130
PHP 17. Tracker_FormElement_Field_ArtifactLink->isValid() /usr/share/tuleap/plugins/tracker/include/Tracker/FormElement/Tracker_FormElement_Field.class.php:969
PHP 18. Tracker_FormElement_Field_ArtifactLink->validate() /usr/share/tuleap/plugins/tracker/include/Tracker/FormElement/Tracker_FormElement_Field_ArtifactLink.class.php:1240