"Blanchard Kahn conditions are not satisfied" problem

I’m writing the code of STRUCTURAL ESTIMATION OF THE OUTPUT GAP: A BAYESIAN DSGE APPROACH (Hirose, Naganuma 2010) but i get this error:

Error using print_info (line 42)
Blanchard Kahn conditions are not satisfied: no stable equilibrium
Error in print_info (line 42)
error([‘Blanchard Kahn conditions are not satisfied: no stable’ …
Error in initial_estimation_checks (line 175)
print_info(info, DynareOptions.noprint, DynareOptions)
Error in dynare_estimation_1 (line 165)
oo_ =
Error in dynare_estimation (line 105)
Error in OutputGapV02 (line 288)
Error in dynare (line 235)
evalin(‘base’,fname) ;

I know that the presence of a singularity problem typically indicates that there is one
redundant equation entered in the model block, while another non-redundant equation
is missing. but i want help to find the mistake in model. Here is the code:

OutputGapV02.mod (3.9 KB)

Your model has a unit root. You need to use the diffuse_filter-option.

If the original calibrated model is stable and can run out of results, what is the reason for the unit root problem in estimation? Is the data used unstable?

No, it’s just a matter of initializing the Kalman filter and correspondingly whether you count unit roots towards stable or unstable roots.