Installed Glade 3.8.5 on my system.
This is done because, Glade 3.8 supports older libglade format and supports all of GTK+2 widgets until the last stable GTK+2.
Working on removing the deprecated widgets from the .glade files.
There are more than 650+ warnings regarding that.
After making sure there are no deprecated widgets in these glade files and that they are in GtkBuilder format that I can move ahead.