A critical vulnerability was discovered in React Server Components (Next.js). Our systems remain protected but we advise to update packages to newest version. Learn More

Jonas Bergqvist
Nov 9, 2012
  7122
(6 votes)

AmbiguousMatchException in MVC BlockController

Have you ever got the following error in the BlockController for our MVC API?

The current request for action 'Index' on controller type 'x' is ambiguous between the following action methods:
System.Web.Mvc.ActionResult Index(y) on type x
System.Web.Mvc.ActionResult Index(y) on type z

If not, you will probably get it in the future. You get this error if you add an action called “Index” in your controller without overriding the index action in the base class. So please, when using a block controller, override the index action, or you may end up with an exception on your EPiServer Tech day presentation.

Nov 09, 2012

Comments

Fredrik Stolpe
Fredrik Stolpe Oct 28, 2014 09:12 AM

A message from the future: I got this error now and this post helped me, thanks :-)

Jens Qvist
Jens Qvist Oct 21, 2015 03:08 PM

Another message from the future. I got this error and this post helped me also! Thanks! :-D

Glenn Lalas
Glenn Lalas Jan 15, 2016 04:53 PM

Chiming in from 2016 to continue the trend of confirming how helpful this post was.  Thanks!  :)

Noel Sefton
Noel Sefton Feb 5, 2019 11:30 AM

yep, helped me as well... (6 years later)

public ActionResult Index(VeryImportantBlock currentBlock) { /*code in here*/ }

becomes

public override ActionResult Index(VeryImportBlock currentBlock) { /* code in here*/ }

Drew Douglas
Drew Douglas Apr 19, 2020 04:27 AM

This post was written 3 months before I got my first professional programming job and 2 years before I had ever hear of episerver, and it's still relavent 7.5 years later. Thanks @JonasBergvist!

Fredrik Stolpe
Fredrik Stolpe May 20, 2020 08:27 AM

Here again, 6 years later :-)

Please login to comment.
Latest blogs
Looking back at Optimizely in 2025

Explore Optimizely's architectural shift in 2025, which removed coordination cost through a unified execution loop. Learn how agentic Opal AI and...

Andy Blyth | Dec 17, 2025 |

Cleaning Up Content Graph Webhooks in PaaS CMS: Scheduled Job

The Problem Bit of a niche issue, but we are building a headless solution where the presentation layer is hosted on Netlify, when in a regular...

Minesh Shah (Netcel) | Dec 17, 2025

A day in the life of an Optimizely OMVP - OptiGraphExtensions v2.0: Enhanced Search Control with Language Support and Synonym Slots

Supercharge your Optimizely Graph search experience with powerful new features for multilingual sites and fine-grained search tuning. As search...

Graham Carr | Dec 16, 2025

A day in the life of an Optimizely OMVP - Optimizely Opal: Specialized Agents, Workflows, and Tools Explained

The AI landscape in digital experience platforms has shifted dramatically. At Opticon 2025, Optimizely unveiled the next evolution of Optimizely Op...

Graham Carr | Dec 16, 2025