ServiceStack update caused all services to 404 - http-status-code-404

Question

We've been running servicestack for quite a while now and have just gotten around to updateing OrmLite and the core ServiceStack libraries with it.
Everything was working great before the update but now the metapage and all services return a 404 - not found page.
Looking at the web.config nothing has changed.
Why is it now returning 404 pages and how do I fix it?
Web.Config:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.0" />
<httpHandlers>
<add path="*" type="ServiceStack.WebHost.Endpoints.ServiceStackHttpHandlerFactory, ServiceStack" verb="*" />
</httpHandlers>
</system.web>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="MySql.Data" publicKeyToken="c5687fc88969c44d" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-6.5.4.0" newVersion="6.5.4.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true" />
<validation validateIntegratedModeConfiguration="false" />
<handlers>
<add path="*" name="ServiceStack.Factory" type="ServiceStack.WebHost.Endpoints.ServiceStackHttpHandlerFactory, ServiceStack" verb="*" preCondition="integratedMode" resourceType="Unspecified" allowPathInfo="true" />
</handlers>
</system.webServer>
</configuration>
AppHost is located on gist here: https://gist.github.com/JohnACarruthers/5366462
Routes 404ing seem to be all of them, metadata and REST urls specifically.
ServiceStack is hosted on mono's fastcgi server through apache, the config of neither has changed.
We're on the current nuget package now (3.9.43.0) and were on 3.9.25.0.
UPDATE:
Mysql.Data was throwing an OverflowException when executing raw SQL. Rolled back to and older version and things seem to work again. The bugged version of Mysql.Data was 6.6.4.0.