Convert QBMB to QBM

With the default backup recovery function of Quickbooks, it should be perhaps possible to recover QBMB files and then export the data in a QBM file, which is what attempts about qbmb to qbm conversion most likely represents. Except for that, there is probably no other way how to achieve this.

In any case, if you have issues with Quickbooks files or their export or conversion, it would be best to contact Quickbooks support or some community resources.