une erreur est survenue

AttributeError: 'NoneType' object has no attribute 'content_type'
CubicWeb version: 3.38.8
Cube mintika version: 2.1.1
Cube seda version: 2.2.0
Cube eac version: 0.8.5
Cube addressbook version: 1.13.0
Cube registration version: 0.13.0
Cube relationwidget version: 0.9.0
Cube squareui version: 1.1.3
Cube bootstrap version: 1.12.0
Cube card version: 1.4.0
Cube compound version: 0.10.0
Cube forgotpwd version: 0.11.0
Cube geocoding version: 0.5.0
Cube prov version: 0.7.0
Cube rememberme version: 1.2.0
Cube skos version: 2.4.0