hexo generate /server csrf_token 错误。 Template render error: Error: Unable to call `csrf_token`

用hexo做blog系统一段时间了，某一天使用
命令 hexo g , hexo s 都报如下错误：
FATAL Something's wrong. Maybe you can find the solution here: http://hexo.io/docs/troubleshooting.html
Template render error: Error: Unable to call `csrf_token`, which is undefined or falsey
    at Object.callWrap (/www/blog/node_modules/hexo/node_modules/nunjucks/src/runtime.js:223:15)
    at root [as rootRenderFunc] (eval at <anonymous> (/www/blog/node_modules/hexo/node_modules/nunjucks/src/environment.js:450:24), <anonymous>:8:67)
    at null.<anonymous> (/www/blog/node_modules/hexo/node_modules/nunjucks/src/environment.js:387:18)
    at Object.exports.withPrettyErrors (/www/blog/node_modules/hexo/node_modules/nunjucks/src/lib.js:24:16)
    at Obj.extend.render (/www/blog/node_modules/hexo/node_modules/nunjucks/src/environment.js:374:20)
    at Obj.extend.renderString (/www/blog/node_modules/hexo/node_modules/nunjucks/src/environment.js:261:21)
    at /www/blog/node_modules/hexo/lib/extend/tag.js:56:9
    at tryCatcher (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/util.js:26:23)
    at Promise._resolveFromResolver (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/promise.js:476:31)
    at new Promise (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/promise.js:69:37)
    at Tag.render (/www/blog/node_modules/hexo/lib/extend/tag.js:55:10)
    at Object.tagFilter [as onRenderEnd] (/www/blog/node_modules/hexo/lib/hexo/post.js:253:16)
    at /www/blog/node_modules/hexo/lib/hexo/render.js:55:19
    at tryCatcher (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/util.js:26:23)
    at Promise._settlePromiseFromHandler (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/promise.js:503:31)
    at Promise._settlePromiseAt (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/promise.js:577:18)
    at Promise._settlePromises (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/promise.js:693:14)
    at Async._drainQueue (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/async.js:123:16)
    at Async._drainQueues (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/async.js:133:10)
    at Immediate.Async.drainQueues [as _onImmediate] (/www/blog/node_modules/hexo/node_modules/bluebird/js/main/async.js:15:14)
    at processImmediate [as _immediateCallback] (timers.js:358:17)