Search the KB for hotfixes.  If you can't find them, rename the 3RDPARTY folder and reinstall SM and the relevant PU.

The error is still persistent after "rename the 3RDPARTY folder and reinstall SM and the relevant PU"

Hi perez kariuki make sure you apply the latest Product Update 5 (as at 20240404) then rename your SG68A folder, open the Sage 300 server installer then run a repair of the install to re-install Account Code Code OR run the installer, modify the install, untick Account Code Change, then once complete repeat to tick Account Code Change.  Also, does Account Code Change work in another database like SAMINC or is it only broken in one entity indicating it might be a data, not application problem?  Please also post a screenshot so we can get a better feel for the error.

Still getting the same error, I have updated to PU5 I have tried it on the SAMINC data still not working, I have also tried the same steps that you have outlined but still giving the same error. Here is an Image of the error