The error is telling you that the logger does not have permissions to write to the log. Assuming the error is coming from Web API and Web API is running on IIS, then you must grant right access to the application pool identity Web API is running under.
Otherwise, you'll need to tell us a bit more about how the logger works. Normal troubleshooting stuff, like provide a code sample that reproduces this issue.
Assuming the error is from Web API then your account does not have permissions to write the unknown log. If your Blazor WASM application is writing the log then the error is expected since Blazor WASM is running in the browser.
Keep in mind, that you still have not provided any meaningful information. Source code that reproduces the issue is a good start. Otherwise, the community is left to guess how your code works.