I managed to get MongoDB running as a three member replica on Windows 8, but I had problems with configuration files. If I used the new (MongoDB 2.6) file format (YAML) and used the replica set name option as:

    replSetName: rs1

(or any of the other variants I had tried in YAML format) I would get "Invalid option: replication" error during the installation. When I switched to old conf. file format and used:


I had no problems. I am very (very!) new to all this, so I am wondering if I was doing something wrong or is it Mongo 2.6 - Windows problem. Thanks!

2 Answers 2


I was not able to replicate, so here's my successful YAML config file (Windows 7 64 bit, MongoDB 2.6.1):

    replSetName: "rs1"
    oplogSizeMB: 512
    dbPath: "data"
    smallFiles: true
    destination: file
    path: "data/mongod.log"

How I started it:

C:\Users\Adam\mongo\2.6.1\bin>mongod.exe -f mongod-yaml.conf
2014-06-03T23:23:12.528+0100 log file "C:\Users\Adam\mongo\2.6.1\bin\data/mongod
.log" exists; moved to "C:\Users\Adam\mongo\2.6.1\bin\data/mongod.log.2014-06-03

And then (after an rs.initiate()):

rs1:PRIMARY> db.serverCmdLineOpts()
        "argv" : [
        "parsed" : {
                "config" : "mongod-yaml.conf",
                "replication" : {
                        "oplogSizeMB" : 512,
                        "replSetName" : "rs1"
                "storage" : {
                        "dbPath" : "data",
                        "smallFiles" : true
                "systemLog" : {
                        "destination" : "file",
                        "path" : "data/mongod.log"
        "ok" : 1

Note that I had issues when I used tabs to indent, which were resolved when using spaces. Case sensitivity was also a problem, but mainly due to muscle memory from the old config options.

  • 1
    Spaces, yes! Thank you, it is working now. I thought it might be something trivial as that :).
    – Aineko
    Commented Jun 4, 2014 at 0:28

Ensure the configuration file uses ASCII encoding. mongod does not support configuration files with non-ASCII encoding, including UTF-8.

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