Files created using 7-Zip Gui v9.29-9.30 can't be read by programs that use old dll library (eg. 4.57).
Reported at Forum: https://sourceforge.net/p/sevenzip/discussion/45797/thread/9d1f5836?limit=25&page=3#94fa
It is a feature rather than a bug. 7-Zip 9.29 uses LZMA2 method by default, which is only supported starting from version 9.04. To retain compatibility, you should manually choose another compression method (for example, LZMA).
UPDATE: Sorry, didn't notice that you used LZMA. Please, post the erroneous archive here. Perhaps, it is OK, but Beyond Compare itself does something wrong.
Yes, I was using LZMA and it happened with any file created in those conditions.
Do you have a way to test if it is a bug with that program or the library, because the error happens only with files created by those newer versions?
Sorry for delay. The simplest thing I think of is to test the archive with an old 7za (7-Zip standalone). If it shows an error, then this is really 7-Zip's problem. If not, the problem is in your application.
Right now I took some time to test old versions against this issue.
My tests were made using the traditional GUI program (7zFM.exe)
Versions 4.58beta and older cannot read files created by 7-Zip v9.26-9.31
These old versions can read files created by the latter versions using LZMA2 but not LZMA.
New 7-Zip uses "Unknown" field in header to align data blocks.
7-Zip 4.50 - 4.58 contain BUG, so they do not support .7z archives with "Unknown" field in header.
Another versions probably work correctly.
Nice to know, thanks.
So, I guess that was fixed in 4.59 as "Some bugs were fixed", right?
Why don't you describe some bugfixes like this? We like big changelogs :)
Moving to other subject... I think that what is more important for you to spend your time on is improving the reliability of compression using multi-core, so it achieves the same compression independently of the amount of cores used. Imo, this is one big downside of 7-Zip compared to WinRAR for example, afaik.