Hi @Christophe Soustelle, Thank you for posting in this community.
This error message in IIS indicates that the method AddGenericAllowedListValue
is not present in the SPFarm
class of the Microsoft.SharePoint.Administration
namespace.
In the September 2021 CU for 2013, 2016, and 2019, Microsoft updated this method. The problem may occur if you are using SharePoint 2016 that is not updated.
You can update your SharePoint 2016 by downloading the SharePoint 2016 update package according to this article: SharePoint 2016 update history.
After the update, please restart IIS and SharePoint Server 2016, and continue your configuration.
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