The error given is simply C1001 Internal compiler error. This problem has been here for a really long time, like I discovered it about months ago. I am on version Visual Studio 2026, version 18.1.1.

Here is a reproducible example.

It simply looks like this:

//main.cpp

import serialisation_module; // error still occurs if you don't import (comment this out)
#include  // doesn't make a difference if this is here or not.

int main()
{

}

And:

//serialisation_module.cppm

module;

#include "glaze/glaze.hpp"

export module serialisation_module;




template 
void read_json(T& obj_out)
{
    char buff[1024];

    static constexpr glz::opts options{ .error_on_unknown_keys = false };


    glz::error_ctx ret_val2 = glz::read(obj_out, std::string_view(buff, 1024));

}

Can someone please report this bug to Microsoft, I don't have an account.