Why can't my other computer open files saved in or later, and why is my tool database read-only there?

Why it happens

Most patches inside a version do not change the file format. Build 12.508 is the exception. The official release notes carry a compatibility note for it:

• Files created by 12.508 or later cannot be opened by 12.507 or earlier.
• Once the tool database has been edited by 12.508 or later, earlier builds can only open it as read-only.

The change was needed to support the Advanced Machining Module, which the official FAQ says requires 12.508 or later. The change applies to everyone who installs the patch, whether or not they own that module.

So two computers can both say "12.5" and still be incompatible, because one is on 12.507 or lower and the other is on 12.508 or higher.

The fix

1. On each computer open Help > About and note the full build number, not just 12.5.
2. Update the older computer with Help > Check for Updates, or download the 12.5 patch from the official Program Updates page.
3. Reopen the file. Files saved by older builds still open in the newer build, so updating is the safe direction.
4. If you share a tool database between computers, update every computer before anyone edits tools, so nobody is locked into read-only.

If the other person cannot update

There is no "save as older build" option described in the official documentation. The practical choices are to have them install the free patch (it is free to every version 12 owner), or to exchange vectors in a neutral format such as DXF or SVG and rebuild toolpaths on their side.

Pro tips

• Update all your computers on the same day. Mixed builds are what cause this problem.
• Back up the tool database before the first run of a new build. See the entry on backing up your tool database.
• For more tool database read-only causes and fixes, including the Windows read-only attribute on the file, see the entry on why the tool database says it is open as read-only.
• For the general "created in a newer version" message across major versions, see the entry on file version compatibility.