Content\obj\WindosGL " /quiet exited with code -532462766

Hi everyone im starting a new project and im a newbie in monogame.
All was working fine and then from nothing this error appeared:

Error 2 The command ““C:\Program Files (x86)\MSBuild\MonoGame\v3.0\Tools\MGCB.exe” /@:“D:\ALT-F4 Game Studios\RTS Project\RTS Project\Content\Content.mgcb” /platform:WindowsGL /outputDir:“D:\ALT-F4 Game Studios\RTS Project\RTS Project\Content\bin\WindowsGL” /intermediateDir:“D:\ALT-F4 Game Studios\RTS Project\RTS Project\Content\obj\WindowsGL” /quiet” exited with code -532462766. RTS Project

Does anyone know what is this error and how to solve it?

You have some assets that do not have an importer or a processor in your pipeline project.