This error occurs at the login screen when the app is trying to load the licensing data.
This is the full error: The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.
To resolve this error:
1) Have the SYSPRO Mobile Warehouse License key available, shouldn't need it but have it just in case.
2) Go to the License folder in the SYSPRO Mobile Warehouse installation directory in Windows File Explorer, default path is:
C:\Program Files\riteSOFT\SYSPRO Mobile Warehouse\License
3) Delete the 2 files in the License folder that end in .cnfg and .acnfg
4) Refresh the SYSPRO Mobile Warehouse Login page.
5) The issue should be resolved but the app may ask for the License key to be entered again.