macOS 26.4’s Script Editor Won’t Open Some Older AppleScripts
Allen Gainsford first reported the issue, noting that many of his BBEdit AppleScripts no longer worked after upgrading to macOS 26.4. Attempting to run them produced macOS error code -1758 (
errOSADataFormatObsolete)[…]Further investigation by Dafuki revealed a nuanced situation. In his testing, many AppleScripts—even some dating back to 2006—continued to run without issues when triggered from apps like BBEdit and Keyboard Maestro. However, others wouldn’t open, and after failing to open one script, Script Editor would then refuse to open any subsequent scripts until it was quit and relaunched.
He found that the issue appears to involve older compiled scripts that rely on legacy storage formats—hence the “data format is obsolete” errors. Allen Gainsford even found that one affected script had a 0-byte data fork and a 26 KB resource fork, indicating that the actual script was stored in the resource fork—a legacy structure macOS supports only for backward compatibility.
Although Script Editor’s 2.11 version number didn’t change from macOS 26.3.1 to macOS 26.4, Apple did increment its build number from 233 to 234, indicating that it received some changes.
A workaround is to use the retired Script Debugger. I wonder whether osacompile could also update the script’s format.
Previously:
