In PLAXIS 3D CONNECT Edition V20.04, when using geogrid elements in your model a Run-time error in kernel  might be encountered.
The error is related to the activation of volume elements that lie on top of a geogrid.
The following simple example explains how the issue is triggered: in Phase_2, the geogrids are activated without any issue, as shown in Figure 1; however, in Phase_3, in which the rest of the embankment (volume element) is activated on top of the activated geogrids, a Run-time error in kernel  occurs, as illustrated in Figure 2.
Figure 1: Phase_2, only geogrids are activated
Figure 2: Phase_3, volume element is activated on top of active geogrids
This issue is now resolved in PLAXIS 3D CONNECT Edition V21 (released January 2021)
When using the above-mentioned version (20.04), the only workaround for this issue consists of activating the option Reset displacements to zero in any subsequent phases in which a volume element is activated on top of an active geogrid element. For more information on the Reset displacements to zero option and how it works, follow the link on See also section at the end of this post.
The option to reset displacements to zero is available in Phases window, under Deformation control parameters, as shown in Figure 3.
Figure 3: Phase_3, successful calculation with Reset displacements to zero option selected
How does Reset displacements to zero work?