If you get a SQL Conversion error of type datetime or other while performing an operation such as a search operation, here's a checklist of items to verify:
Upgrade your DB schema from Manage Keys / Sites / Upgrade DB Schema
Change the Default Language of the SQL user that is configured in the connectionString as follows:
Launch SQL Server Management Studio
Expand the Security node
Expand the Logins node
Locate the QLM user configured in your connectionString (by default qlm_user)
Right mouse the user and select Properties
In the General section, set the Default Language to English
