Intelligently redirect to v1 if no v2 project found for token

services/web/app/coffee/Features/TokenAccess/TokenAccessController.coffee

@@ -3,9 +3,19 @@ AuthenticationController = require '../Authentication/AuthenticationController'
 TokenAccessHandler = require './TokenAccessHandler'
 Errors = require '../Errors/Errors'
 logger = require 'logger-sharelatex'
+settings = require 'settings-sharelatex'
 
 module.exports = TokenAccessController =
 
+	redirectNotFoundErrorToV1: (err, req, res, next) ->
+		if err instanceof Errors.NotFoundError and settings.overleaf
+			logger.log {
+				token: req.params['read_and_write_token']
+			}, "[TokenAccess] No project found for token, redirecting to v1"
+			res.redirect(settings.overleaf.host + req.url)
+		else
+			next(err)
+
 	_loadEditor: (projectId, req, res, next) ->
 		req.params.Project_id = projectId.toString()
 		return ProjectController.loadEditor(req, res, next)

services/web/app/coffee/router.coffee

@@ -426,6 +426,7 @@ module.exports = class Router
 				maxRequests: 10,
 				timeInterval: 60
 			}),
-			TokenAccessController.readAndWriteToken
+			TokenAccessController.readAndWriteToken,
+			TokenAccessController.redirectNotFoundErrorToV1
 
 		webRouter.get '*', ErrorController.notFound