Is there a way to prevent the LastPass browser extension from filling out a HTML-based form with a input field with the name \"username\"?
This is an hidden field,
Here's what worked for me to prevent lastpass from filling a razor @Html.EditorFor box in Chrome:
Click the active LastPass icon in your toolbar, then go to Account Options > Extension Preferences.
On this screen check "Don't overwrite fields that are already filled" (at the bottom)
Next, click "advanced" on the left.
On this screen check "Respect AutoComplete=off: allow websites to disable Autofill".
I did not need to do anything special in my ASP cshtml form but I did have a default value in the form for the @Html.EditorFor box.
I hope this helps and works for someone. I could not find any Razor-specific help on this problem on the web so I thought I'd add this since I figured it out with the help of above link and contributions.