You might see this error when using the latest IBISCHK6 tool, due to a known issue with v5.0 .ibs files generated for Intel® Arria® 10 or Intel® Stratix® 10 devices by the Intel® Quartus® Prime Pro Edition Software version 17.0 or later.
This error is seen because the Maxwell capacitance Kij (i/=j) values in the Capacitance Matrix of the Package Model are positive, which do not comply with specification.
Specific examples of the error message are as follows:
ERROR - Package 10ax115_f11520: The Capacitance Matrix has off-diagonal element 3.000000e-016 at row AK11 col AJ10 which is positive
ERROR - Package 1sg280h_f17600: The Capacitance Matrix has off-diagonal element 1.000000e-016 at row K30 col N30 which is positive
This problem is scheduled to be fixed in a future release of the Intel® Quartus® Prime Pro Software.