When you try loading attribute page of a Project / task form with attributes, the page pops with multiple error that reads: Ajax call unsuccessful. Status: 404.
Attribute value doesn't load.
The Ajax error is not a WebCenter issue. It is because the IIS restriction set is limited to load database tables.
By default, the Maximum query string size is set to 2048 bytes in IIS Manager > Request Filtering. After upgrading to WebCenter 16 / 16.1, it demands for more bytes to query string / load database tables. Since default size set for Query size in IIS is lower, it will have issue loading database tables in Attributes page of a project.
Please find the procedure to change / update query string size in IIS:
Log on to WebCenter WebServer.
Go to IIS Manager > WebServer "Name of WebServer" > Request Filtering.
Change the Maximum query string (Bytes) value from 2048 to 4096.