Await js.InvokeVoidAsync("openWindowWithContent", htmlContent) throws exception

I'm using blazor server side and core.On my razor page I have this code in the "code" section.

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I have a code behind file that contains:

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I have a code behind file that contains:

I use this same code in other projects and they run without fail. When I call print in this application, I get this exception:

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Anyone have a suggestion as to what this issue might be. The only difference between this app and the other apps that run it is the htmlcontent. I checked for malformed html by replace the string with the htmlcontent from another working application, but it still fails.

Googled for a answer but didn't find anything.

I replaced the HTML content being sent with HTML content from a working application and it still failed.