The below issue has been existing for DotNetNuke Map module for a significantly long time.
Map Module Edit: Critical Error

I was recently surprised to see that the latest DNN 5.2.1 release still features the old Map Module 01.00.09 version, that was compiled against DNN 4.x, and throws exceptions when run in DNN 5.0. I originally posted this here and here, on the same thread that the Module just needs a recompilation against DNN 5.x, and it would work fine.

However, as most people (especially non-technical ones) would have had problems compiling a DNN module from source, I provided links to the Map module dll that I compiled against DNN 5.x, and runs successfully on it.

Now for my readers of the DotNetNuke 5.x book, of which I am a technical editor, I am again attaching the compiled dll below, and re-enumerating the steps to get the Map module going in DNN 5.x:

1. Install the Map module normally in DNN 5.x from the Host > Extensions > Install Available Extensions
2. Check the checkbox for the Map module, and note its version.
3. Click “Install Selected Extension”.
4. After the module installs successfully, and if your Map module version was (01.00.09), download the file attached below.
5. Copy the downloaded file in the bin folder of your DNN installation. If asked for replacement, make sure to replace/overwrite the existing file. Dont keep both copies, as this could cause your installation to throw errors.

That should be it. Try using the Map module, and it should work fine.