Hi Dave, Appended below is my original email with the input files attached. Thank you very much for helping with this. Manish -----Original Message----- From: Sharma, Manish (sharmamh) Sent: Friday, March 11, 2016 12:36 AM To: nektar-users-bounces@imperial.ac.uk Subject: Requesting some help with the Adaptive SFD algorithm Dear All, I am fairly new to nektar++, and have been trying to simulate the flow in a lid-driven cavity using the adaptive SFD method. However, after the first stability analysis run, I get the following output and error.   Iteration: 1 (residual : 8.559e-27) Writing: "SquareCavityNonuniform110x110-AdaptiveSFD1.fld" L 2 error (variable u) : 1.60644e-14 L inf error (variable u) : 3.59318e-14 L 2 error (variable v) : 1.48736e-14 L inf error (variable v) : 3.72109e-14 L 2 error (variable p) : 1.01877e-14 L inf error (variable p) : 5.76926e-17 Fatal   : Level 0 assertion violation Unrecognised value. I have checked my input files thoroughly, but am unable to understand what this error of "Unrecognised value" mean, or, how it has occurred.  For your convenience/reference, the Geometry/Mesh, the nonlinear problem definition, and the homogeneous linear problem files are attached. Any suggestions/solutions to resolve this issue will be greatly appreciated. Thank you, Manish