Tool to validate a web.config

Is there a tool that I can use to validate my web.config? The reason I ask is that the file appears to be valid XML and IIS is complaining that file is invalid. No explanation or indication as to why.

Thanks in advance.

Edit:

HTTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid. Detailed Error Information: Module IIS Web Core Notification Unknown Handler Not yet determined Error Code 0x8007000d Config Error
Config File \?\C:\DignityFiles\Source\simplicity\Simplicity\web.config Requested URL http://simplicity-local.dignitytest.co.uk:80/ Physical Path
Logon Method Not yet determined Logon User Not yet determined Config Source:

-1: 0:

More Information: This error occurs when there is a problem reading the configuration file for the Web server or Web application. In some cases, the event logs may contain more information about what caused this error.

View more information » [This takes you to "https://support.microsoft.com/en-gb/help/942055/-http-error-500-19-error-when-you-open-an-iis-7-0-webpage"]

Link to the web.config (Note: sensitive information has been redacted)

I have (eventually) found the answer: https://stackoverflow.com/a/41267673

Installing the URL rewrite module fixed my issue.