@panagiotis-charalampous Check in the logs directory for any error.
I'm guessing authorization is not enabled on the database as it is not enabled by default. Use the link @Duke gave and follow the 'Configure MongoDB' section.
While visit ACP Page, this error was throwed.
Is is a config problem, or others?
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: 2018-04-07T15:43:46.960Z [30948] - error: [acp] Failed to fetch latest version TypeError: The header content contain
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at validateHeader (_http_outgoing.js:494:11)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at ClientRequest.setHeader (_http_outgoing.js:498:3)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at new ClientRequest (_http_client.js:173:14)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Object.request (http.js:38:10)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Object.request (https.js:239:15)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Request.start (/data/nodebb/node_modules/.registry.npm.taobao.org/request/2.83.0/node_modules/request/request
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Request.end (/data/nodebb/node_modules/.registry.npm.taobao.org/request/2.83.0/node_modules/request/request.j
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at end (/data/nodebb/node_modules/.registry.npm.taobao.org/request/2.83.0/node_modules/request/request.js:561:14
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Immediate.<anonymous> (/data/nodebb/node_modules/.registry.npm.taobao.org/request/2.83.0/node_modules/request
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at runCallback (timers.js:794:20)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at tryOnImmediate (timers.js:752:5)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at processImmediate [as _immediateCallback] (timers.js:729:5)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: 2018-04-07T15:43:46.983Z [30948] - error: [acp] Failed to fetch latest version TypeError: The header content contain
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at validateHeader (_http_outgoing.js:494:11)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at ClientRequest.setHeader (_http_outgoing.js:498:3)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at new ClientRequest (_http_client.js:173:14)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Object.request (http.js:38:10)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Object.request (https.js:239:15)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Request.start (/data/nodebb/node_modules/.registry.npm.taobao.org/request/2.83.0/node_modules/request/request
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Request.end (/data/nodebb/node_modules/.registry.npm.taobao.org/request/2.83.0/node_modules/request/request.j
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at end (/data/nodebb/node_modules/.registry.npm.taobao.org/request/2.83.0/node_modules/request/request.js:561:14
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at Immediate.<anonymous> (/data/nodebb/node_modules/.registry.npm.taobao.org/request/2.83.0/node_modules/request
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at runCallback (timers.js:794:20)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at tryOnImmediate (timers.js:752:5)
Apr 07 23:43:46 jdu4e00u53f7 nodebb[30925]: at processImmediate [as _immediateCallback] (timers.js:729:5)
@a632079 what is your site title? If you change it to just letters, does the error still occur?
@a632079 if you change the title to just "NodeBB" does it start working?