Please help me for below error.

translateKey (/opt/NodeBB-0.9.0/public/src/modules/translator.js:175:14)
11/12 02:20 [23370] - error: /forum/auth/facebook
MongoError: topology was destroyed
at Server.update (/opt/NodeBB-0.9.0/node_modules/mongodb/node_modules/mongodb-core/lib/topologies/server.js:979:49)
at Server.update (/opt/NodeBB-0.9.0/node_modules/mongodb/lib/server.js:331:17)
at updateDocuments (/opt/NodeBB-0.9.0/node_modules/mongodb/lib/collection.js:980:19)
at Collection.update (/opt/NodeBB-0.9.0/node_modules/mongodb/lib/collection.js:1018:44)
at /opt/NodeBB-0.9.0/node_modules/connect-mongo/lib/connect-mongo.js:360:18
at MongoStore.getCollection (/opt/NodeBB-0.9.0/node_modules/connect-mongo/lib/connect-mongo.js:216:11)
at MongoStore.set (/opt/NodeBB-0.9.0/node_modules/connect-mongo/lib/connect-mongo.js:358:10)
at Session.save (/opt/NodeBB-0.9.0/node_modules/express-session/session/session.js:71:25)
at Session.save (/opt/NodeBB-0.9.0/node_modules/express-session/index.js:331:15)
at ServerResponse.end (/opt/NodeBB-0.9.0/node_modules/express-session/index.js:289:21)
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (http.js:690:11)
at ServerResponse.header (/opt/NodeBB-0.9.0/node_modules/express/lib/response.js:718:10)
at ServerResponse.contentType (/opt/NodeBB-0.9.0/node_modules/express/lib/response.js:551:15)
at ServerResponse.send (/opt/NodeBB-0.9.0/node_modules/express/lib/response.js:138:14)
at defaultFn (/opt/NodeBB-0.9.0/src/middleware/render.js:19:11)
at /opt/NodeBB-0.9.0/src/middleware/render.js:73:8
at /opt/NodeBB-0.9.0/public/src/modules/translator.js:156:6
at /opt/NodeBB-0.9.0/public/src/modules/translator.js:177:4
at Object.translator.load (/opt/NodeBB-0.9.0/public/src/modules/translator.js:206:5)