SharePoint 2013 - “Change the Look” breaks when editing master page

Question

I'm trying to make some changes to a master page, the thing I actually want to do is test the ReplaceColor attribute within the CSS, however it seems as soon as I do so, the whole 'change the look' system breaks. Has anyone experienced this or can anyone make some suggestions on what I might do to fix it? These are the steps I've taken:

1. Create a new Publishing Site
2. Map a network drive to the http:\machineName_catalogs\masterpage

then either modify the built in master page:

1. Change the Look to one that uses the oslo master page (I chose sea monster).
2. Edit the oslo.html in the mapped network drive.
3. Modify the example DIV to read - "This area will be filled in by content you create in your page layouts!". That is, change a '.' to a '!'.
4. Attempt to change the look again (the preview never loads, clicking ok causes an error - detailed below).

I've also tried creating a minimal master page and going through the same steps (I copied oslo.preview to ensure it would appear in the change the look, I redirected the master page of sea monster in composed looks to my new master page, I published my master page). This gave me exactly the same error.

The preview never loads:

The error message as captured by the ULS log is:

The layout URL submitted to the Design Builder is invalid.
System.ArgumentException: Value does not fall within the expected range.
at Microsoft.SharePoint.SPWeb.GetFile(String strUrl)
at Microsoft.SharePoint.ApplicationPages.DesignEditor.EnsureMasterPageIsValid(String layoutUrl) StackTrace:
at onetnative.dll: (sig=6aba1f5f-ccc4-4590-af00-b8ffe7fe99a0|2|onetnative.pdb, offset=28BE6)
at onetnative.dll: (offset=152A9)

Even if I revert the change the HTML file for the master, this doesn't fix the 'Change the Look'. I need to replace the .master with an original to fix it. Very frustrating!

Answer 1

I would not mess with out-of-the box master pages as you're doing. It's better to create a copy of these one and work straight on the .master file or going the .htm road and uploading your template, converting it to a master page (this steps is mandatory)and then solely relying on the converted html file which will reflect changes to its binder .master file. Relevant snippets will be included on the .html file to fulfill your needs.

If the sea monster is filling your needs (guess the developers loved that giant squid recently caught on tape!), a customized xml theme might be enough.

Benjamin Niaulin has a detailled walkthrough on that process : http://bniaulin.wordpress.com/2012/07/18/sharepoint-2013-design-manager-convert-html-to-master-page/ and Randy Drisgill (http://blog.drisgill.com/) has a nice codeplex project with well documented master pages to help you (and you also have a nice twitter bootstrap 2013 branding on codeplex!)

On my side, for my current projects, I went to the classic .master provisioned without relying on the design manager (with a separate master for internet audience), never managed (yet) to have extreme branding using the provided snippets.