Using MRO language with Anaconda

Microsoft R Open (MRO) is the enhanced distribution of R from Microsoft, a complete and free open source platform for statistical analysis and data science.

MRO was previously the default R interpreter in Anaconda. As of 2019 releases, Anaconda defaults to internal builds of R, henceforth the “Anaconda R ecosystem.” Learn more about how to use R with Anaconda.

Anaconda maintains an archive of MRO packages but will not update MRO packages. Support for MRO packages will be on a case-by-case basis.

If you are using MRO, it is recommended to migrate to R. Follow the migration directions below.

Migrate MRO conda environments to use Anaconda R

If you have an MRO-based conda environment and you want to shift over to Anaconda R to fix library errors or for updates, using conda will fail:

conda install r-base

Using conda will result in unsatisfiable errors because the MRO packages in your environment will conflict with Anaconda R counterparts. They’re not compatible and the metadata is designed to prevent this coexistence. You can create a new environment but that could require more effort depending on how many dependencies you have.

To resolve this, use the MRO-migrator tool. This tool removes all MRO-specific packages then updates the remaining packages to use Anaconda R instead of MRO. The remove-update cycle takes care of the unsatisfiability.


There’s minimal error handling in this tool. If your environment is not readily reproducible, back it up before running this tool.

To use the MRO-migrator tool, run its command line:

mro-migrator ~/miniconda3/envs/your-r-env

The default behavior lists which MRO-only packages will be removed. The tool does not change anything by default. To perform a migration, pass the --execute flag:

mro-migrator --execute ~/miniconda3/envs/your-r-env

MRO-supported operating systems

64-bit systems only for all operating systems - Windows, macOS, and Linux.

Windows 7.0 SP1, Windows 8.1, Windows 10, Windows Server 2008 R2 SP1, and Windows Server 2012.

Linux - CentOS, Red Hat Enterprise Linux, Debian, and Ubuntu.

When using MRO conda packages, starting the R interactive interpreter shows Microsoft R Open in the startup message. Anaconda Navigator, the Anaconda graphical package manager and application launcher, also creates R environments by default. You may instead select MRO when creating a new conda environment from within Navigator.

Microsoft R Client

Microsoft R Client is a free, community-supported data science tool for high-performance analytics built on top of MRO. Additionally, R Client introduces the powerful ScaleR technology and its proprietary functions to benefit from parallelization and remote computing.

Microsoft R Client is available as a conda package (r-mrclient). Users of Windows or RHEL-7/CentOS7/Ubuntu 14.04 and above also have the option to conda install the MicrosoftML R package for machine learning (r-mrclient-mml) and the pre-trained models for sentiment analysis and image detection (r-mrclient-mlm).

Creating a new environment with MRO instead of R

When creating a new environment, you can use MRO and not R by explicitly including mro-base in your list of packages.

With conda 4.6.4:

conda create -n mro-environment r-essentials mro-base
conda activate mro-environment

Switch an environment from R to MRO

We recommend using R as your default interpreter in Anaconda, however the directions below show you how to switch an environment from R to MRO.

Activate the environment containing R

If you use conda 4.4 or later, run:

conda install mro-base

If you use conda 4.3, run:

conda remove --force r-base  _r-mutex
conda install mro-base

The environment’s R interpreter will switch from R to MRO.

mro-basics: The MRO Basics metapackage contains everything in the Microsoft MRO installers. It does not include r-mrclient, r-mrclient-mml, or r-mrclient-mlm.

r-mrclient: Microsoft R Client is a free, community-supported, data science tool for high performance analytics.

r-mrclient-mml: MicrosoftML provides state-of-the-art fast, scalable machine learning algorithms and transforms for R. Depends on r-mrclient.

r-mrclient-mlm: MicrosoftML Machine Learning Models are pre-trained machine learning models for sentiment analysis and image detection. Depends on r-mrclient-mml.