{"\":\" is not valid at the start of a code block. Only identifiers, keywords, comments, \"(\" and \"{\" are valid.\r\n"}

This error basically means something went wrong in Razor markup. When I try to google it, I see some results for this error message instead:

{"\"@\" is not valid at the start of a code block. Only identifiers, keywords, comments, \"(\" and \"{\" are valid.\r\n"}

 
 

...so that's an at symbol instead of a colon and the threads I find from Google suggest just doubling up the at symbol as @@ so that Razor does not misinterpret it. I can't even find in the code base I'm looking at the colon which is so objectionable. Whatever.