Unable to add new records to database via MyLittleAdmin in Plesk: example.com redirected you too many times

Symptoms

• Unable to add a new record to MSSQL database via MyLittleAdmin at Domains > example.com > Databases > MyLittleAdmin > User Databases > Tables > Add record:

  CONFIG_TEXT: mssql.example.com redirected you too many times

• The following error can be seen in the browser's console:

  CONFIG_TEXT: http://mssql.example.com/obj/errors.aspx?t=%3cstrong%3eMessage%3a%3c%2fstrong%3e+A+potentially+dangerous+Request.QueryString+value+was+detected+from+the+client+(t%3d%22%3cstrong%3eMessage%3a%3c%2fst...%22).

Cause

ASP.NET has a feature called request validation which prevents script-injection attacks. It detected that the request contained some possibly malicious code and therefore blocked it.

Resolution

If the request is considered safe, the following steps can be applied as a workaround:

1. Connect to the server via RDP.
2. Create a backup of file %plesk_dir%MyLittleAdmin\web.config
3. Open %plesk_dir%MyLittleAdmin\web.config​ with a text editor. Then add the following line marked in bold:

   CONFIG_TEXT: validation="SHA1" />
   <httpRuntime
   maxRequestLength="204800"
   requestValidationMode="2.0"
   />
   <browserCaps>
   ...

4. Add the new record to MSSQL database via MyLittleAdmin at Domains > example.com > Databases > MyLittleAdmin > User Databases > Tables > Add record