Upgrading from 3.4 to 3.6

I had a database running version 3.4 so i went to upgrade to 3.6 and i guess the final step of 3.4 upgrade was never done. Now i get the following error and it wont run 3.2 or 3.4 or 3.6. I get the same error on all versions

** IMPORTANT: UPGRADE PROBLEM: The data files need to be fully upgraded to version 3.4 before attempting an upgrade to 3.6; see http://dochub.mongodb.org/core/3.6-upgrade-fcv for more details.

Welcome to the MongoDB Community Forums @Andrew_Yost !

The expected fix is per the documentation link in the error message: you need to set the featureCompatibilityVersion (“FCV”) to 3.4 to complete your upgrade to 3.4 and enable features that persist backwards-incompatible changes to data files. You should do so while your deployment is running a 3.4.x version of MongoDB server.

Now i get the following error and it wont run 3.2 or 3.4 or 3.6.

The “upgrade problem” error message should only be displayed if you are trying to open data files with an FCV older than the MongoDB server release servies.

Before continuing, can you confirm:

  • The recent backups you have available relative to your upgrade attempt (for example, do you have a backup before starting the upgrade process)

  • Your deployment type (standalone, replica set, or sharded cluster)

  • Specific version of MongoDB 3.4.x server you were running before and after the upgrade


I think i was running 3.4.1 I do not have a backup. and it is standalone. the data is not overly important. but would like to keep it if i could