Gate driver IR2110 problems
Not sure about the LTSpice error, but I do see one problem.  In order for the high side IR2110 to work, the bootstrap capacitance (C1 and C3) must be charged so that 12 volts appears across it.  This is done by pulling the VS pin to ground, which happens every time you switch the low side on a normally-configured half bridge.  In your circuit, this capacitor will not ever be charged.  C1 and C3 must be refreshed periodically by pulling VS to ground; the charge on the cap provides the current and voltage necessary to get the high side gate drive voltage to a voltage greater than your 12 V supply.    If the charge on this cap is less than 8 volts or so, the high side switch will shut off.  You could put in the low side FET instead of D2 and pulse it at the start and then again periodically.