Version 12b Patch

Version 12b Patch Information

This page outlines the enhancements and bug fixes that are included in the version 12b patch. It is important to understand that a patch is not a full game download; it includes only the changes that have been made since version 12 was first released.

Because the version 12 game and the version 12 encyclopedia are downloaded as separate Windows programs, we have created patch files for both. If you use the Encyclopedia, you'll need to download and install both patches to incorporate all the changes.

The version 12b patch comprises all bug fixes and enhancements introduced since the initial release of version 12. Installing this patch is all that is needed to ensure that your copy of Diamond Mind Baseball is fully up to date.

Please keep reading to find out about the changes in the version 12b patch. You'll learn how to check if you already have version 12b installed and how to download and install the version 12b patch to update your already installed copies of the version 12 game and encyclopedia.

Enhancements in the version 12b patch

  • Added support for allowing a player to both pitch and DH in a game (the "Ohtani rule"). Includes updates to the computer manager to allow player to remain in game as DH if removed as pitcher and vice versa.
  • Added support for limiting pickoff throws by the pitcher.
  • Updated Historical Ballpark database to include all parks through 2023. 
  • Updated Historical Player database to include all players through 2023.
  • Updated Historical Era database to include all eras through 2023.
  • Increase maximum limit for Playing Time Penalties to 500% (limit was 250%)
  • Improved substitution logic when saved lineup includes a player without a position.
  • When migrating a database league Era IDs will be carried forward to the New season database, if possible, instead of assigning the Neutral Era.
  • Add check for in-progress games when converting a database with option to delete saved games and continue or reject the conversion.
  • Added three new transaction type pairs: 7 Day IL/Activate, Shutdown/Return, Paternity/Return.
  • Improved Computer manager logic for pinch-hitting for platoon partner when protecting a late lead.
  • Update fielding reports to display baseball notation for part innings (i.e. .1 and .2 instead of .3 and .7)
  • Added additional schedule templates for schedule formats that were originally excluded from version 12.
  • Updates to the play-by-play library. Includes support for new features and various fixes.
  • Increased the saved database limit. It is now possible to have more than 200 database references.

Bug Fixes in the version 12b patch

  • Various fixes for adding new column headings in customized and memorized reports.
  • When working with depth charts, Move and Exchange menu commands now include additional utility player slots.
  • When the bullpen warmup rule is enabled, replacing an injured player with a pitcher that has not been warming will not generate a warning message.
  • Corrected issue in Saved lineups that caused unsaved lineups to be erased when a new lineup/depth chart is computer generated.
  • Fixed standings report to correctly show extra-inning records for scheduled games of all lengths.
  • Corrected issue with the Update streaks & usage command that would result in a crash when there are no remaining unplayed scheduled games.
  • Tidied up field names and column headings in Batting profiles and Pitching profiles reports.
  • No longer possible to inadvertently insert a pinch hitter from the player bench menu after a game has been completed.
  • Corrected postseason bracket display for teams with a bye in the previous round. 
  • Fixed error when deleting the last season in an encyclopedia (ENC).
  • Fixed bug that caused tiebreaker "Playoff" games to be excluded from the season standings and displayed in the schedule incorrectly (ENC).
  • Fix for bug that caused boxscore files to be saved to an incorrect location when generating a website (ENC).
  • Fixed HTML table formatting for season leaders and career Leaders reports (ENC).
  • Opening multiple scheduled games simultaneously is no longer supported. Doing so in the past could result in database corruption.
  • Corrected an issue with the Migrate command that sometimes led to the assignment of no park or an incorrect park for a team.
  • When using the Copy command from the Teams tab in the Organizer, manager names are now accurately copied.
  • When a dual role player is both pitching and serving as the DH in a game, they can now continue as the DH if removed as the pitcher due to a rain delay.
  • No longer possible to play a scheduled game while the schedule editor window is open.

Note: Changes added in 12b are in bold

Keeping track of versions

If we release multiple patches, each one will be labeled with a different letter, such as a, b, c, and so on. We'll also update the master file for new downloads of the version 12 game. If you bought DMB12 after the latest patch, you probably don't need to download and install additional patches, as those corrections are likely already included in the version you downloaded from the Diamond Mind website.

To find out whether your copy of DMB12 has already been updated, start the game and from the Help menu, click About Diamond Mind Baseball. If the window that pops up reads "version 12b", you know you already have the corrections that have been made to date.

DMB Leagues

For leagues based on the 2023 season database, it's important that all members upgrade to version 12b. This update ensures compatibility with the new "Pickoff Throw rule" and the "Starting Pitcher as DH rule."

Even if your league isn't using the 2023 season, we still recommend upgrading to version 12b. This way, the game will work consistently for all managers in your league.


If your league uses NetPlay for any of its games, all members must be using the same version of the software to connect. This means everyone should upgrade to version 12b to guarantee NetPlay compatibility. Remember, you won't be able to connect in NetPlay if one computer is using version 12 or 12a and another is using version 12b.

Downloading the patch

To download the patch installation file, click the link provided below to open the download page on the Diamond Mind website.  From the download webpage, click the "Download Now" button to start your download.

When you download the file, your browser might automatically start the download or ask where to save it. If it asks, choose a location on your computer to save the file. Typically, files downloaded from the internet are saved in the Downloads folder of your Windows profile.

If your web browser shows a warning and stops the download of the patch installation file, please see the following topic on the Diamond Mind message board for a solution.

"File isn't commonly downloaded" browser warning - Diamond Mind Baseball (

Installing the patch

After downloading and saving the patch installation file to your computer, you can install it by locating the file named "dmb12b_patch.exe" (it might also appear as "dmb12b_patch") using Windows Explorer or another file browsing tool. Double-click on this file to start the installation process.

Before you install the patch, complete any games currently in progress and make sure that DMB is completely shut down.

During the installation process, you will be prompted to choose a location for the updates. The installer will suggest "C:\dmb12" (or "C:\dmbenc12" for the encyclopedia), the same as the original installation. If you chose a different location when you first installed DMB, be sure to specify that same location for the patch installation.

Installing the patch will not affect any of your settings or any of your player ratings, statistics or other data that is stored in a DMB database. After installing the patch, you can continue to use DMB12 and your databases without interruption of any kind.

Download Links

Download the DMB 12b patch (6.24 MB)

Download the DMB Encyclopedia 12a patch (1.12 MB)