# Is there a way to check a blend file's integrity, and/or see a crash log?

I have a Blend file (my Yoda model) that I started back in 2005, when Blender was probably still in 2.3 or 2.4 territory. I've slowly updated him over the last 11 years, implementing new features, refining and what not. But it seems that more and more often when I'm editing the mesh or just doing random things, Blender crashes, and I'm wondering if it may be that some random feature I've used along the way, or old modifier or some little bit of data that is corrupting the file, or if it's just Blender being Blender (or really, software being software).

So, my questions are: a. Is there a crash log that I don't know about that I could try to see why I'm crashing? b. Is there a blend file integrity checker?

As far as I know there is no blend "file auditing" tools, but I may be wrong.

There are however debugging options in Blender. You can launch blender using command line options to activate it's debugging tools and see if any useful output can help you pinpoint your problem. You can see all debug options at the Blender Manual

If you are on Windows you should probably also set up a batch script or a specific shortcut to automatically launch Blender with the correct arguments without having to write them manually each time.

A batch script is also useful to prevent the command prompt from closing automatically in the event of a crash, so that you can actually see what happened and read the output history. It could go something like:

start C:\Windows\System32\cmd.exe /k path\to\Blender.exe --debug-memory


Replace "debug-memory" with whatever you need like "debug-all".

If you model is not too complex (rigged, or animated or with physics) and you don't risk loosing important data you may also force flush a cleanup of settings by exporting it to a non-blender format (like OBJ, or FBX, or 3Ds) so that it is stripped of any settings, preferences or additional Blender specific data that may have gotten corrupt throughout the versions.

Remove any modifiers that you may easily add again later and export only a pure raw base mesh of your Yoda model, and then re-import it in a brand new fresh blend file, so that any settings or outdated information is left behind, and only the clean mesh data is kept, then manually recreate any modifier stack you had.

Your file may also be of use to the developers if the crashes can be reliably reproduced so they can fix any bugs that cause them, although now is probably not a good time with the start of 2.8 development just around the corner big changes are expected, and backwards compatibility won't be a priority.

• Thank you for the suggestion of debug mode and keeping the console window open after a crash, going to try that! Unforunately there are lots and lots of UV-Maps, Weight Groups and Animation Rigs. At some point I may go through a process of copying them over to a stripped mesh, as you suggested, but hopefully debugging will find the errors. – Blazer003 Sep 27 '16 at 20:36

1. I would attempt to open the file in an earlier version of blender.
If that works, export as a .dae (or .obj or others if that's not available), then reopen in the newer version of blender. You'll loose some things, but perhaps that's better than nothing.

2. Also if your file opens in an older Blender, you may be able to start a new file with that version, append just what you need from the old file, then save and see if you can open that file in the newer version of blender. Perhaps some extra cruft is having problems with the newer version.

3. If your file does not open in the older version of Blender, the file was corrupted somehow... I can't help you there, but perhaps a blender developer can.

4. Do you have an earlier backup of the project that does not have this problem?

Blender make this easy: save myproject001.blend when you're ready to save the next one, save as, then press the "+" to increment the file name. this changes it to "myproject002.blend, hit return, and keep working.

I've learned the hard way that I need to make new files often. I often have over a hundred versions of my project, I can restore all or part from an older version if something bad happens, or if change my mind on something.

EDIT: I reread the question. I see, the file opens, but randomly crashes. Perhaps some of these ideas will still help. Is the crash repeatable? I can you repeate the action that crashed it to make it happen again? (that would offer some clues.) If not, it could also be a computer hardware problem, use a memory checker tool, test on other computers...