FCPX XMLD problems, crash on import

Hi, probably a question for Joema. I’m assisting an editor and I’ve been having problems with exchanging XMLs. FCPX always crashes on importing the XMLD. I would like to try the “hidden” project repair tool, but I have to be able to see what it repairs. Could you point me towards what you use to compare XMLs?  I have a suspicion that it’s related to retimings using optical flow and will try to find some time to run some tests on his set. 
Many thanks for past discussions and posts. Often invaluable

It would help to know the HW on which things are running, as well as the FCP version and the macOS version (and the FCPXML version).

Holding option and clicking on the Clip menu and choosing Verify and Repair Project does the "hidden repair" function (as you probably know). BBEdit (free version) can do a quite good job showing file differences (you'll need to compare the actual FCPXML file insde the fcpxmld package). Joe uses BeyondCompare a lot, which  isn't free.

I discovered that if a FCPXML file references a PDF file, the import will fail (if the PDF isn't in the same (relative?) position on your drive(s)). Of course, import errors aren't crashing, so that's a big difference. Joe can add to this...

There are others on the forum more experienced at FCP XMLs, but I'll give a few comments. On more recent versions of FCP, it seems there have been increased reports of problems with XMLs. We have spent a lot of time investigating this, but I don't think we yet have a clear picture. We don't have any tools for repairing XMLs; we mainly look at them in an XML-aware text editor such as BBEdit, and try to figure out what they mean. BBEdit can also do a color-coded "diff" comparison of different text files, including XMLs. Sometimes that helps to see differences in similar versions.

FCP crashing during XML import doesn't necessarily mean there's a problem with the XML. Ideally, FCP should never crash. There are various FCP XMLs: clip, project, event and library. Do you suspect the project was damaged because FCP crashed when importing a project XML?

We have no information on what the undocumented project repair tool does. I would suggest caution when using that.

If you could post the FCP crash log somewhere, we could try to evaluate that.

Possibly the fastest workaround is don't use XML but instead use a "transfer library". Procedure:

(1) First ensure all your media is imported using "leave files in place", otherwise the library will be too large to send.
(2) Delete all render and proxy files from source library, via File>Delete Generated Library Files>Delete Render Files>All, also delete proxy and optimized media. If that is not feasible, this procedure will not be practical.
(3) Delete all analysis, optical flow, thumbnail and waveform files. There is no FCP command to do this. You have three options:
(a) Use the third-party tool Final Cut Library Manager: www.arcticwhiteness.com/finalcutlibrarymanager/
(b) Or: use Finder to go inside the library and then delete the "render" folder inside each event (exercise great caution).
(c) Or: Use the FCP library inspector's Storage Locations>Modify Settings, and define a folder for "Cache". That will place all render, optical flow, analysis, waveform and thumbnail files in a single bundle within that folder. That bundle can be safely deleted in Finder.
(4) Create a new event on the source machine.
(5) Copy (do not move) your project to that "transfer event"
(6) Rename that project to something unique, such as "SandroProjectUpdates062623".
(7) Create a new library on the source machine, which will be the "transfer library".
8.  Copy or move the transfer event to the transfer library
(9) Close that transfer library, zip it and send to recipient.
(10) On the destination machine, unzip and load that transfer library
(11) Copy or move the transfer event from the transfer library to the working library
(12) In the working library, open the project in the transfer event and examine it.

Anytime you work with XMLs or transfer libraries, it is more reliable if all media have unique filenames. Also, all FCP media and libraries should only be on APFS or MacOS Extended Journaled disk volumes.

Thank you both. We're running on a variety of hardware. Editor's main rig is an iMac Pro. I'm running 15 inch Intel 2018 and 16 inch M1 Max. This library still on 10.6.5. XML version 1.10
I can't get to the editor's rig till the end of the week & will run some tests then. I've run into this problem before and did as Joema suggested, libraries and copying events. That works. 
(media is always external and treated as if original media. I make the proxy media with Resolve)
Tried to import in 10.6.1/6.5 & 6.6. Intel Mac also crashes
These are the first lines from the crash report:

Crashed Thread:        0  Dispatch queue: com.apple.main-thread
Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:       KERN_PROTECTION_FAILURE at 0x000000016a68fe00
Exception Codes:       0x0000000000000002, 0x000000016a68fe00
Termination Reason:    Namespace SIGNAL, Code 11 Segmentation fault: 11
Terminating Process:   exc handler [3715]

I need to see the entire crash log, however it is too long to post in-line. That log will be viewable in the MacOS Console app, under "Crash Reports". Right-click on the FCP Crash report, pick "Reveal in Finder". That will point to an .ips file. If there is more than one FCP crash log, send them all. Zip those files and upload to this location:

  www.dropbox.com/request/BVXc9IOr2kpLsGXTN3Wm 

Please also ZIP the XML file and upload to the same place. We don't need to see your media, just the XML file. I'll forward it to Dave in case he has time to examine it.

Yes I often use Beyond Compare which has nice features. However it is still Intel, not Apple Silicon, although it runs well under Rosetta. BBEdit is native Apple Silicon and is much faster when comparing large documents. Also, when examining things like XMLs you frequently need to incrementally filter out noise results and do various searches. BBEdit is excellent at that and can use regular expressions.

I send you the log & xml. Thanks

Your XML reliably crashes FCP 10.6.2 and 10.6.6 on my M1 Ultra machine running Ventura 13.4.1. The XML passes DTD validation using the MacOS built-in 'xmllint' utility. That implies the XML is well-formed and there are no structural errors. Therefore the problem may be in the logical or semantic information unique to FCP which is wrapped by the XML syntax.

While the XML is complex, the file size isn't that large. I could possibly file a bug just using that file. I am so busy on my "real work" I may have to do that, since troubleshooting stuff like this takes an immense amount of time.

The crashing stack trace is interesting -- it is extremely long (over 500 frames) and appears to involve some type of recursive processing. In your case the crash happened when comparing two strings, taking into account locale-specific rules for character comparison and sorting. See attached. In my case the stack trace was similar but it crashed during a merge sort.

Thanks. It won't affect the handoff as I'll make a copy of the whole library, but I'm puzzled & want to know how to avoid this the next time. Appreciate all your help. Once I have the library end of the week I'll try to find some time to export some xml's and import them again. Perhaps there'll be something retimed with optical flow, had trouble with that before.

Dave suggested this: can you export the XML, then import that  XML on the same machine to a test library? That should be totally safe, but please make a file-level duplicate of  your library using Finder beforehand. We expect it will crash like before. If it does not crash that might steer the investigation in another direction.

The purpose is to exclude any possibility of some difference between machines being a factor. 

Joe, thanks for looking into this issue. Much appreciated!

I'll report back once I have the library this weekend. Thanks

I filed this today using the MacOS Feedback Assistant tool as bug #FB12463033. Thanks to DaveM for his help.

Made a copy of the library. Genuinely strange. I did a couple of tests. XML of the whole sequence crashes on import into a new library. Then I split the project in 2 and these XML's import without crashing. X2Pro has no problem reading the XML of the whole timeline. Still have to check if sync and automation have all carried over, but at first glance it looks good. No time to check on the original Mac.