Hi sunjac,
I received this error again after leaving Fusion open overnight while regenerating time consuming tool paths in CAM. Document was saved successfully immediately before starting this operation (and walking away from computer). Tonight (~24hrs later), got above errors when trying to save.
Recreating the proteinrun directory does not seem to help:
cmason@fire2:~> ps auwwx | grep -i fusion
cmason 40059 1.3 2.8 8118596 476692 ?? S 6:47PM 57:49.61 /Users/cmason/Library/Application Support/Autodesk/webdeploy/production/7a3b2d2378fae3fb9ca6087aa2563a5ab7a9d68f/Autodesk Fusion 360.app/Contents/MacOS/Autodesk Fusion 360
cmason 40063 0.0 0.0 2655252 7524 ?? S 6:47PM 0:01.35 /Users/cmason/Library/Application Support/Autodesk/webdeploy/production/7a3b2d2378fae3fb9ca6087aa2563a5ab7a9d68f/Autodesk Fusion 360.app/Contents/Frameworks/AIRMAX/adexmtsv /Users/cmason/Library/Application Support/Autodesk/Common/Material Library/15102001/adexmtsv_prod.cfg -p /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/Neutron//15102001cmason
cmason 43325 0.0 0.0 2445076 812 s000 S+ 6:36PM 0:00.00 grep -i fusion
cmason@fire2:~> ls -l /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/
total 0
drwxr-xr-x 2 cmason staff 68 Dec 18 18:36 Neutron
drwxr-xr-x 2 cmason staff 68 Dec 18 18:35 TemporaryItems
cmason@fire2:~> mkdir /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/proteinrun
[Retry save.]
cmason@fire2:!> ls -l !$
ls -l /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/proteinrun
[No files in this directory after retrying save.]
cmason@fire2:/usr/local/src/grbl> ls -l /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/
total 0
drwxr-xr-x 2 cmason staff 68 Dec 18 18:37 Neutron
drwxr-xr-x 2 cmason staff 68 Dec 18 18:35 TemporaryItems
drwxr-xr-x 2 cmason staff 68 Dec 18 18:37 proteinrun
Where shown above, I tried saving the document again (twice) and got:
Error: /Stage/BB15.9_0921_MAC/BB15.9/Protein/src/xirang/xirang/vfs/vfs.cpp(410)failed to create temp file in directory:
Error: Save of document Wallet Minimal 2 v35 failed
Error: /Stage/BB15.9_0921_MAC/BB15.9/Protein/src/xirang/xirang/vfs/vfs.cpp(410)failed to create temp file in directory:
Error: Save of document Wallet Minimal 2 v35 failed
I also looked at creation time of tmp directories:
cmason@fire2:~ ls -ld -tU /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/
drwxr-xr-x 5 cmason staff 170 Nov 6 13:47 /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/
cmason@fire2:~> ls -l -tU /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/
total 0
drwx------ 8 cmason staff 272 Dec 18 18:31 T
drwxr-xr-x 6 cmason staff 204 Nov 7 06:52 0
drwx------ 13 cmason staff 442 Nov 6 13:47 C
cmason@fire2:~> ls -ld -tU /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/Neutron
drwxr-xr-x 3 cmason staff 102 Dec 18 18:34 /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/Neutron
cmason@fire2:~> ls -l -tU /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/Neutron
total 0
drwxr-xr-x 5 cmason staff 170 Dec 18 18:57 ToolbarFramework
cmason@fire2:/usr/local/src/grbl> chmod a+rwx /var/folders/yb/f6cp9tzx0bz1l86xb55scd0h0000gp/T/
[Retried save, still failed.]
I'm not exactly sure what these T, O, C dirs correspond to (are they from other processes/applications?) but it does seem like the T directory that Fusion is using was recreated around the time I started using Fusion again tonight. I'm not sure what would be removing this directory, if that's indeed what happened. I don't have antivirus or any other cleanup software installed. I do have several other applications open during the same time, including: Parallels, Evernote, Messages, Safari, Chrome, iTunes. I will try this again tonight where Fusion is the only app open. I also open and shut the computer's lid several times during the day while Fusion was running in background.
I also now get a recurring message about not being able to create a Recovery file:

I've attached Diagnostic log files here.
Can you help me understand what's going on here so I can help troubleshoot more effectively? Should I expect this directory to:
a) contain files related to my open and unsaved document, while I'm using Fusion, or,
b) simply be used *during* the save process, or
c) something else?
LMK what other information I can provide. Now that I know that I basically can't successfully leave Fusion running overnight, I'm less likely to loose data, but it's unfortunate for these scenarios involving lenghty tasks.
Thanks,
-c