Looks like the issue is STRCONV(data,1). In Vista compatibility mode, the resulting data is simply incorrect. STRCONV(data,2) appears to work in both modes.

Jon

>Folks,
>
>We have a VFP POS application that uses a C# DLL for displaying and printing BMP images generated from captured signature data. The data itself is sent from VFP via STRCONV(bSignatureData,1) to the C# library which then performs Convert.FromBase64String() on the passed byte data. Below is the data that the DLL is receiving:
>
>

/////wICMQT+ATYE+AFBBO0BVQTnAV8E3QFzBNgBgwTYAYcE4AGGBOgBgAQCAmcEFAJWBD4CKgRrAvsDgQLkA6gCuwO5AqsDxgKeA9YCkQPYApUD1AKdA84CqAO8AskDsQLdA5cCCwR7Aj0EbgJVBGMCawRRApAETAKdBE8CpwRXAqQEcwKOBIYCfAScAmkEygI9BPcCEQQKA/0DKgPeAz0DzQNCA8oDRAPKA0ID1QM5A+oDMwP3AycDFwQbAzgEFgNJBBMDVwQVA2wEGQNxBCEDcwQ7A2sEXQNWBHEDRwSYAygEqwMZBLsDCwTXA/UD5gPrA+oD6wPsA+0D6AP7A+ADEgTcAx8E0gM8BM8DSgTMA1cEywNtBNADegTVA3wE4wN5BOsDdQT8A2oEBQRkBBQEWwQcBFkEIwRZBDQEXgRKBGgEWARtBH0EdASSBHUE/////w==

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>My tech department informs me that some of our clients need to run our application in Vista SP2 compatibility mode to work properly (maybe a Win10 thing?). When being in this compatibility mode, the C# convert throws an exception stating that the data passed is not a valid Base64 string. However, when the application is not run in compatibility mode, everything works fine.
>
>Any ideas as to what Vista SP2 mode is lacking?
>
>Jon