Dear support team,

I tried to use GAMS and Kestrel a while and it worked fine. Recently, I downloaded the new GAMS version (30.1.0 re01a340 WEX-WEI x86 64bit/MS Windows) and I activated it by using a trial licence. Now, I’m trying to solve an optimization model using GAMS/Kestrel. When I run the GAMS to solve the model it has the following error:

— Starting compilation

— GAMS…Kestrel.gms(43) 3 Mb

— Starting execution: elapsed 0:00:00.013[LST:48]

— GAMS…Kestrel.gms(38) 4 Mb

— Generating MIP model sequence[LST:48]

— GAMS…Kestrel.gms(43) 4 Mb

— 58 rows 73 columns 272 non-zeroes

— 36 discrete-columns

— Executing KESTREL: elapsed 0:00:00.033[LST:266]— Kestrel fatal error: GAMS cntr-file version 41, 42, 44, 46, 47 or 48 required

ERR: Solver rc 1

— Restarting execution

— GAMS…Kestrel.gms(43) 2 Mb

— Reading solution for model sequence[LST:281]

*** Status: Normal completion[LST:330]

— Job GAMS…Kestrel.gms Stop 04/03/20 17:55:45 elapsed 0:00:02.128

The input is:

```
MODEL test/ all /;
Option mip=kestrel;
$onecho > kestrel.opt
kestrel_solver Cplex
neos_server www.neos-server.org:3333
$offecho
test.optfile=1;
SOLVE test using MIP minimizing PRS;
```

Would you please,

- What does it mean and how can I fix this issue?
- Can Gurobi solver be invoked through the kestrel using the GAMS new versions? (In the previous version it did not)

Regards

A. Omidi