# Mathematica 9 does not read mathematica 8 “.mx” files

Having written a lot of code on M8, I recently switched to M9 and tried to run the code on M9, the code starts by loading an .mx file written by M8, but M9 wouldn't read the .mx file saying that it was written on another machine. This is a major incompatibility issue between M8 and M9. Fortunately, I kept my M8 installation, so for now, M9 is useless to me. Please a solution.

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@OleksandrR. You should post this as an answer, preferably with links to the relevant docs. –  jVincent Dec 10 '12 at 11:27
@jVincent I don't think it really matters in this case since nothing more can be said on this question than is written in the documentation, ergo it will sooner or later be closed as TL (and I will vote as such as soon as the OP acknowledges the response). However, I've now given an answer as you suggest. –  Oleksandr R. Dec 10 '12 at 11:52
@OleksandrR. I believe the documentation is lacking in this regard in that .mx files are mentioned in several locations without mention of the non-compatibility with version changes. While it's true that there are also locations that do mention it, I believe that this question has value in directing users who for instance read the DumpSave documentation which states only machine dependence. –  jVincent Dec 10 '12 at 12:13
This question should remain open as a visible warning to new users. This is a bad mistake to make if proper back-ups were not kept. –  Mr.Wizard Dec 10 '12 at 13:49
Just curious -- given that versions get updated and hardware gets updated from time to time, why do people use *.mx files? ...I guess I can see the usefulness for shorter term storage. –  Mike Honeychurch Dec 10 '12 at 22:49

Or read them in in v8 again and Save them. This format is compatible. –  Sjoerd C. de Vries Dec 11 '12 at 6:27