Is it possible this is a problem with my hardware or software? Or with the particular things I've modified in Blender? I've tried re-downloading Blender 2.7; I'm definitely using Sugar. I have made changes in all the levels on the right labeled S4Studio, and also the rig. My graphics card is an Intel(R) HD 4400 and I have a 64 bit operating system and a 3.4 GHz processor.
And I
think I'm following these steps as you've outlined them.
You said:
--Sims 4 Studio imports and exports .blend files.
To do this open your .package in Studio and click on the Meshes tab.
Check
---This will bring you to a page with a drop down menu. By default LOD 0 is selected. This is the highest quality LOD that is seen from close up in the game. If you click the export button under that drop down Studio will export the LOD and the format it exports it in is .blend.
Check. I've done this under multiple different names, too, and none of the .blend files open.
---If you open that LOD.blend in Blender you will see the meshes.
Check. Yes, and then I've made changes to the mesh. At least, I'm pretty sure I'm seeing the meshes; they respond the same way other peoples' meshes do in youtube tutorials.
---If you then make a change to the mesh or meshes and save your .blend
again, done this
--you can go back to the Meshes tab section in Studio and click the import button to bring the LOD with your edited meshes into the .package.
Check, I think. I've tried leaving s4s open throughout the meshing and then importing the changed mesh back to the original cc creator's mesh I'm modifying. I've tried opening the .blend file on it's own, just right clicking and selecting "open with" s4s. I've also tried with an adult-to-child hair, a hat, and a sofa. I didn't modify the rig at all with the hat or the sofa; that was sort of an accident with the hair.
...and that's when I get the error message.
The Sims 4 Studio - Version 2.6.1.2
S4Studio.Data.IO.Package.PackageLoadException: Failed to load E:\Blender Meshes\professorlilith.Sintiklia_-_Hair_s35_DivaSintiklia_ATC.test.blend ---> System.IO.InvalidDataException: Not a Sims package.
at S4Studio.Data.IO.Package.DBPFHeader.Read(Stream stream, IReferenceList resources) in C:\Workspace\Sims4Studio\TheS4Studio\S4Studio.Data\IO\Package\DBPFHeader.cs:line 211
at S4Studio.Data.IO.Package.DBPFPackage.Load() in C:\Workspace\Sims4Studio\TheS4Studio\S4Studio.Data\IO\Package\DBPFPackage.cs:line 98
at S4Studio.Data.IO.Package.DBPFPackage..ctor(String filename, Boolean cache) in C:\Workspace\Sims4Studio\TheS4Studio\S4Studio.Data\IO\Package\DBPFPackage.cs:line 69
--- End of inner exception stack trace ---
at S4Studio.Data.IO.Package.DBPFPackage..ctor(String filename, Boolean cache) in C:\Workspace\Sims4Studio\TheS4Studio\S4Studio.Data\IO\Package\DBPFPackage.cs:line 73