Certain versions of ASP.NET do not correctly recognize the latest version of Windows Internet Explorer and must be updated.
When ASP.NET does not correctly recognize Internet Explorer, it responds with a "_doPostBack is undefined JavaScript" error.
To resolve this issue, do one of the following:
- Revise the application to use feature detection, rather than browser detection (preferred).
- Update the ASP.NET browser definition files.
Related topics
Internet Explorer compatibility cookbook