Blender to Collada rigged weights failing now after a year of working perfectly - HELP!

[HeatherD Tungsten]

Starting yesterday, all the exports of my mesh object from Blender to Collada format files are not transferring the weight painting correctly.  I am modeling my own female avatar and clothes.  I have been trying to trouble shoot the problem.  It turns out that if I do a test upload of one of my previous DAE files I created, the upload works perfectly.  But since yesterday, any new rigged mesh or models that I have previously made (even my body that I have been using for months) and do a new export to a new DAE file, then take that file and upload it to blender, the weights are no longer valid.   When I look at the model in the Second Life Upload Window preview panel, and click the check box for Skin Weights, the model collapses in on itself to a thin tangle.  The models since yesterday turn into a mess within Second Life.
I am using the same procedure to upload mesh items that I have been using for the last year.  Note; I do not use AvaStar.  I use a stock version of BLENDER 2.79 as it is loaded to my computer from Blender.org  
I do not think that I inadvertently reset something, but I can't be sure.   I am currently trying to find a listing of all the settings, check boxes, and even units that I need to set within Bender in order to confirm that I have the right setting, in order to enable me to continue to export to Collada and on to Second Life.  Right now, I am effectively dead in the water and can't move forward on my project.  HELP!
Any one who could point me to a list of setting or a tutorial would be a real help.
The first image is my project so far, Bento head armature, Classic body armature.  The next two show the Shorts I am trying to upload and how that mesh weight is messed up.

Edited November 5, 2017 by HeatherD Tungsten

[Aquila Kytori]

hi

  Just wanted to point out something that appears to be wrong in the of the mesh uploader screenshots.

The shorts are huge !

Looks like something is not quite right with the scaling in Blender.

I have almost no experience of rigging and weight painting so have no idea if this is the cause of your problems or not but would suggest you check that scale has been applied and also that you haven't somehow mixed Imperial and Metric units  together.

Scaling the uploaders X,Y and Z dimension by 0.3048  (feet to meters) does give a more realistic size for the Bounding box of an Avatars shorts.

 

 

[Chic Aeon]

The new versions of Blender from 2.78 on changed the way that the blur brush in particular worked. I do not make clothes but this has been well documented with clothes makers including a long term high profile designer friend of mine. The only fix that they had was to go BACK to their old version of Blender that WAS working. One designer is using both and switching back and forth. Blender wouldn't let me install and older version when I had a newer one, but I believe it will let you install and new one and KEEP the old. 

 

So your issue could easily be something related to that --- I know not. 

 

A thought in case the older stuff was made with an older version of Blender which seems very likely. Good luck. 

[HeatherD Tungsten]

Hey Aquila, Thanks for pointing that out to me.  I have never noticed that before, but I have noticed that all my mesh is very big as it first is rezzed, and then I am guessing that the sl armature adjusts the size to the slider setting of my avatar.  I am not sure how this works but I have not had any problems in world.  I think Chic may be on to something as I did recently update the version of BLENDER.  The weird thing also is that my problem is only with mesh using the classic armature.  My head uses the Bento Armature and it uploads fine.
???