One of the HTTP status and sub-status code pairs is 500.19. It translates into “Configuration data is invalid”. Please note that IIS may show this pair incorrectly if a user terminates the request before the website is loaded completely.
The error message from a sample Failed Request Tracing log is below
HttpReason: Internal Server Error
ErrorCode: An operation was attempted on a non existent network connection (0x800704cd)
When a user drops the connection, IIS generally log one of these code pairs: 200.0.995, 200.0.64, 206.0.995 or 206.0.64. (That the last part of the codes is sc_win32_status). However, you may see 500.19.64 for certain cases: