2019-04-29 20:21:40.259389+0300 SET[10419:570991] [LayoutConstraints] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want.
    Try this:
        (1) look at each constraint and try to figure out which you don't expect;
        (2) find the code that added the unwanted constraint or constraints and fix it.
(
    "<NSLayoutConstraint:0x600001b97930 'fittingSizeHTarget' UIStackView:0x7fd7d2508530.width == 0   (active)>",
    "<NSLayoutConstraint:0x600001b97070 'UISV-canvas-connection' UIStackView:0x7fd7d2508530.leading == UIButton:0x7fd7d2502af0'Button'.leading   (active)>",
    "<NSLayoutConstraint:0x600001b970c0 'UISV-canvas-connection' H:[UIButton:0x7fd7d251ffd0'Button']-(0)-|   (active, names: '|':UIStackView:0x7fd7d2508530 )>",
    "<NSLayoutConstraint:0x600001b97250 'UISV-fill-equally' UIButton:0x7fd7d251f850'Button'.width == UIButton:0x7fd7d2502af0'Button'.width   (active)>",
    "<NSLayoutConstraint:0x600001b972a0 'UISV-fill-equally' UIButton:0x7fd7d251fcb0'Button'.width == UIButton:0x7fd7d2502af0'Button'.width   (active)>",
    "<NSLayoutConstraint:0x600001b973e0 'UISV-fill-equally' UIButton:0x7fd7d251ffd0'Button'.width == UIButton:0x7fd7d2502af0'Button'.width   (active)>",
    "<_UISystemBaselineConstraint:0x600001cb76c0 'UISV-spacing' H:[UIButton:0x7fd7d2502af0'Button']-(NSLayoutAnchorConstraintSpace(8))-[UIButton:0x7fd7d251f850'Button']   (active)>",
    "<_UISystemBaselineConstraint:0x600001cb7780 'UISV-spacing' H:[UIButton:0x7fd7d251f850'Button']-(NSLayoutAnchorConstraintSpace(8))-[UIButton:0x7fd7d251fcb0'Button']   (active)>",
    "<_UISystemBaselineConstraint:0x600001cb78a0 'UISV-spacing' H:[UIButton:0x7fd7d251fcb0'Button']-(NSLayoutAnchorConstraintSpace(8))-[UIButton:0x7fd7d251ffd0'Button']   (active)>"
)

Will attempt to recover by breaking constraint
<_UISystemBaselineConstraint:0x600001cb78a0 'UISV-spacing' H:[UIButton:0x7fd7d251fcb0'Button']-(NSLayoutAnchorConstraintSpace(8))-[UIButton:0x7fd7d251ffd0'Button']   (active)>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.