When storing source code in the library, the source code is compressed to save space. The compression algorithm (V1) used by EmCompressor>>#compress is sensitive to both the platform it is running on and to the current locale. This means that it may be impossible to decompress some source code if the platform or locale is changed after the source code is saved.

A new compression algorithm (V2) is introduced that is not affected by the execution platform or the current locale, and a matching new decompression function is added to the native and server library access primitive modules:

In short, any image connecting to a manager with >= 8.6.2 code in it will need to use the new library primitives distributed with 8.6.2 or beyond.  Older library primitives cannot properly decompress source created by the new library primitives.

On Windows these library primitives are called emntv50.dll and emsrv50.dll. On Unix they are libemntv50.dll and libemsrv50.dll. Copy these from >= 8.6.2 installations and replace the files with the same name found in < 8.6.2 installations. All versions of VA Smalltalk installed on the system should now have updated library primitives.

The migration from the old compression algorithm to the new algorithm is, by definition, imperfect since there is no way to change old images or old primitives. However, with a little care there should be no problem.

Looking at the table, you can discern that old library primitives should never be used when accessing a library containing V2 compressed source code. However, since the issue only manifests itself during decompression, there is no damage to the content of the library if old library access primitives are used. To help remind you of this, new images will report a warning on the Transcript when they start if they are connected to the library using old library primitives.