"This operation is not permitted" when using custom plug-in (on some PC's)

Hi,

Wonder if anyone can assist please?

We have a plug-in which has been working fine for years.

When used it saves a copy of the .PDF being worked on.

We have 2 PC's which have just upgraded to the same Adobe DC version (2019.012.20034) - using the same document:

-One one machine it works fine without any errors.

-On the other we get 'This operation is not permitted'.

This occurs when the PDDocSaveWithParams command is called.

Any help would be greatly appreciated. (Wondered if it was font related).

Regards

Stuart

saveParams->fileSys=ASGetDefaultFileSys();

saveParams->newPath=pathName;

saveParams->saveFlags=PDSaveFull|PDSaveLinearized|PDSaveCollectGarbage;

saveParams->size=sizeof(_t_PDDocSaveParams);

saveParams->saveFlags2 = PDSaveCompressed | PDSaveAddFlate | PDSaveReplaceLZW | PDSaveOptimizeXObjects | PDSaveOptimizeContentStreams | PDSaveOptimizeFonts;

PDDocSaveWithParams(pdDoc,saveParams);