Hi,

check if your molecule have SO2 or SO groups... then change the sulfur atom type to plain "S" and try again.

The sulfur atom type is already "S".

I had the same issues..... but interestingly cgenff server only support topologies for the following sulphur types..

### Supported S atoms in CGenFF

MASS  -1  SG2D1     32.06000 ! thiocarbonyl S

MASS  -1  SG2R50    32.06000 ! THIP, thiophene

MASS  -1  SG311     32.06000 ! sulphur, SH, -S-

MASS  -1  SG301     32.06000 ! sulfur C-S-S-C type

MASS  -1  SG302     32.06000 ! thiolate sulfur (-1)

MASS  -1  SG3O1     32.06000 ! sulfate -1 sulfur

MASS  -1  SG3O2     32.06000 ! neutral sulfone/sulfonamide sulfur

MASS  -1  SG3O3     32.06000 ! neutral sulfoxide sulfur

Regards