1054 - Unknown column 'passwordconvert' in 'field list'

[Jones H]

Hi, it seems that you run only some parts of the merge system. Usually that plugin is automatically activated after those fields have been added. Normally they're used to allow logging in with the same password used on the old software. Also the provided solutions aren't the proper ones:

• Adding the define statement disables the whole plugin system so none of your plugins will run which is troublesome if you decide to use MyBB in the future.
  
• Simply deleting the file may result in future issues as the plugins to load are stored in the database so the system may throw an error as it tries to load a plugin which doesn't exist anymore
  

The proper solution would be to disable the plugin in the acp (configuration -> plugins) before deleting that file.