SiteCore - JSON showing on the pages where controls should be in the page editor

I'm in the page editor and I'm seeing JSON where editor controls should be

{"commands":[{"click":"chrome:field:editcontrol({command:\"webedit:chooseimage\"})","header":"Choose Image","icon":"/~/icon/SoftwareV2/16x16/photo_landscape.png.aspx","isDivider":false,"tooltip":"Choose an image","type":null},{"click":"chrome:field:editcontrol({command:\"webedit:editimage\"})","header":"Properties","icon":"/~/icon/SoftwareV2/16x16/palette_preferences.png.aspx","isDivider":false,"tooltip":"Modify image appearance","type":null},{"click":"chrome:common:edititem({command:\"webedit:open\"})","header":"Edit the related item","icon":"/temp/IconCache/Software开发者_开发知识库V2/16x16/cubes_blue.png","isDivider":false,"tooltip":"Edit this item in the Content Editor.","type":"common"}],"contextItemUri":"sitecore://master/{2D90E98C-1360-4EBA-855E-3B321B053376}?lang=en&ver=1","custom":{},"displayName":"Logo","expandedDisplayName":null}

This is happening in the page editor but not when I view the site.

Solved. It was because I removed the < form method="post" runat="server" id="mainform" > from the page. Added it back in. Best if you make it the first child under < body >

I also recently encountered this issue and the resolution for me was to make sure the 'webedit.css' file existed at the location specified by the 'WebEdit.ContentEditorStylesheet' setting.

By default the webedit.css file is located at the root of your site, but in my instance the file had been moved.

We had this error because of commented out HTML above the DOCTYPE declaration. Removing the commented out HTML fixed the problem.