An error occurred while parsing EntityName
A bare ampersand (&) in text or in an attribute.
The message, as .NET reports it
An error occurred while parsing EntityName. Line 1, position 17.
Why it happens
- An unescaped
&: a company name, a URL query string. - XML built with string concatenation or interpolation instead of an XML API.
How to fix it
Write & for every literal ampersand. XmlWriter, XElement and XmlSerializer escape it for you; SecurityElement.Escape does it for a string.
.NET throws an XmlSchemaValidationException at the first schema error unless XmlReaderSettings.ValidationEventHandler is set, which then receives every one with its line and position. A well-formedness error is an XmlException and ends reading whatever the settings.
The same problem in xmlvalid
xmlvalid validates with libxml2, which reports it as xmlParseEntityRef: no name. It checks the whole document in your browser and lists every schema error with its line and column, not only the first.
xmlParseEntityRef: no name
Example
Reports the error
<company>Smith & Sons</company>
Fixed
<company>Smith & Sons</company>