Sage appears to blame some type of corruption:
Resolution
Uninstall Sage Exchange Desktop (Start, Control Panel, Programs and Features)
- Open C:\ProgramData
- Right-click 'Sage Payment Solutions'
- Rename to 'Sage Payments Solutions_old'
- Open C:\Users\UserName\AppData\Local\Sage Payment Solutions (where UserName = Windows username)
- Rename the Sage Exchange folder located here to Sage Exchange.Old
- Browse to the MAS90\Wksetup folder and run Autorun.exe
- Select the option to install Sage Exchange Desktop
- Proceed with the installation and test SE once it finishes
- Module SDK should be repaired during this process, but for older versions, it is possible you might have to manually repair it.
https://support.na.sage.com/selfservice/viewdocument.do?noCount=true&externalId=86122&sliceId=1&cmd=displayKC&dialogID=27924&docType=kc&isLoadPublishedVer=&stateId=27926&docTypeID=DT_Article&ViewedDocsListHelper=com.kanisa.apps.common.BaseViewedDocsListHelperImpl