Instant VB FAQ

Q: Are the original C# files altered in any way?

Your existing code is left completely intact. The new VB.NET project is output to the new location that you specify.

Q: What version of C# is converted?

We attempt to convert as much as possible and are continually updating the converter to handle newer C# features. However, many new C# features have no VB equivalent so the output will require adjustments.

Q: Do you guarantee a 100% complete conversion?

No — our accuracy is very high, but there will be some adjustments required for all but the simplest conversions. Read the rest of the FAQ to get an idea of a few things that are not converted.

Q: What type of code is not converted?

'unsafe' code blocks and types are not converted.
ASP.NET script.
Code having statements fragmented by preprocessor conditions. Processing stops for a file when this type of situation occurs.
e.g.,
    int i =
#if FOO
        0;
#else
        1;
#endif

The file can only be converted if the above code is rewritten as:
#if FOO
    int i = 0;
#else
    int i = 1;
#endif

Q: What are the most common adjustments necessary after conversion?

VB does not allow assignments within expressions, but C# does (e.g., while ((x = y()) > 0) assigns a value to x as part of an expression). Instant VB will convert some cases, but will mark other more complex cases with a 'task' comment. You must manually adjust these.
Most reference type comparisons are converted, but occasionally you may need to manually change an equals sign to "Is". The VB compiler makes these adjustment requirements obvious.
VB does not allow overloading when it is based only on the direction of the parameters (ByVal vs ByRef). Methods overloading done this way will require renaming of the method name in VB.
Project conversions never produce auto-generated files, such as the Resources.Designer.vb or Settings.Designer.vb files. For .NET Core projects, these should be automatically re-generated (may require saving the resources or settings), but for .NET Framework projects, after conversion you will need to right-click on the "Settings.settings" file within Visual Studio and select "Run Custom Tool" to force auto-generation of the Settings.Designer.vb code file. Similarly, you will need to right-click on the "Resources.resx" file within Visual Studio and select "Run Custom Tool" to force auto-generation of the Resources.Designer.vb file.
Unfortunately, many new C# features beginning with C# 7 have no equivalent in other languages.

Additional Resources

VB.NET and C# comparison and equivalents chart

C# – Visual Basic bilingual dictionary