ExcelDNA error after upgrading to Visual Studio 2026

[Laurent Beaumer]

I have recently upgraded from VS 2022 CE to VS 2026 CE.

For the exact same code, running properly with VS 2022 CE, I have an error with VS 2026 when loading the Add-in Excel:

<< Registration [Error] Repeated function name: 'IsErrorOrEmpty' - previous registration will be overwritten.  >>

"IsErrorOrEmpty" is not an Excel function (i.e. not registered using "ExcelFunction"). 

It a public static method to assert if the value of Excel parameter is "ExcelEmpty" or Null.

Adding << ExplicitRegistration="true" >> in the DNA file had no effect.

I have tried version 18.0.1 and 18.0.2 with the same error.  

I will try to isolate the file where the code is causing the issue but it may take sometime.

I understand without access to the (proprietary code) where is not much to go on.

I think it still is worth being reported.

Thank you