It is strange that this issue happens only to one user.
Is he using a business role different from other users? Please check SAP KBA :
1823758 - Exception CX_CRM_UI_DC_PARAM_NOT_DEFINED when creating
Interaction Record
It is strange that this issue happens only to one user.
Is he using a business role different from other users? Please check SAP KBA :
1823758 - Exception CX_CRM_UI_DC_PARAM_NOT_DEFINED when creating
Interaction Record