Web site with MS SQL server database show Internal Server Error 500.19

Symptoms

Website with database on MSSQL server shows 500.19 Internal Server Error, error code 0x8007000d.

CONFIG_TEXT: HTTP Error 500.19 - Internal Server Error

Error Code
0x8007000d

Config Error
Configuration file is not well-formed XML

Config File
\\\\?\\C:\\Inetpub\\vhosts\\domain.tld\\httpdocs\\web.config

Config Error
Configuration file is not well-formed XML

Config Source:
13: <add name="SQL DB" connectionString="Data Source=.\\MSSQLSERVER2014;Initial Catalog=db-name;Integrated Security=False;User Id=UserName;Password=MyPass&word;" providerName="System.Data.SqlClient" />

Cause

Special characters in connection string were not escaped.

Resolution

Since the web.config is XML, the following special characters have to be escaped:

CONFIG_TEXT: &amp; -> & ampersand, U+0026
&lt; -> < left angle bracket, less-than sign, U+003C
&gt; -> > right angle bracket, greater-than sign, U+003E
&quot; -> " quotation mark, U+0022
&apos; -> ' apostrophe, U+0027

Go to Plesk > Domains> example.com > File Manager and edit web.config file and replace all special characters according to the table above. Example, MyPass&word = MyPass&word