Cannot return to "China"-updated: Success

I forget; do you use mods? Specifically, NRaas ErrorTrap, Overwatch, and Traveler would be very useful here.

If not, the best thing to do is to reduce the stress of the travel transition as much as possible before sending your sims back. Use "save as" to rename the save (so you have a backup), empty out your sims' personal inventories as much as you're willing (WA chests come in handy here), and turn down all the graphics options down to the minimum. (Memories are also a drag on performance, for future reference, but disabling them probably won't do much good at this point.) Turn off the in-game shopping experience and the hidden object loading screens as well. Then quit to desktop and clear your cache files.

When you're reloading, don't sign in at either the launcher or Main Menu. Send your sims right after loading, and then if they arrive safely, "save as" again and quit to desktop. Then you can change your graphics settings back to normal. But without mods, you might end up with your sims stranded in China and unable to get back. Sooner or later, the fragile travel transition will probably break again unless you take steps to protect your game.

Thanks for advice. I do have Overwatch and Traveler. Never had a problem before with high options or travelling but will try turning down. Have emptied inventory except for what is needed for trip. Always save as. But will also try not signing in.

So I tried all the options I could find with no results. Thank goodness for saves.

Finally I decided to take a detour through France. Did some shopping, visited a few friends. Stayed for the full three days (may be the key). Came home and just in case worked a day. Then successfully travelled to China and completed another leg of my adventure.

Not positive but thinking maybe because when i completed the task in France ( dragon keystone) and then came home early then I maybe messed up traveling to China to deliver? So by going back to France and spending full time it triggered something? I still had the keystone and didn't do any tasks second time so who knows but I'm just happy ( I mean my sim is) to continue on her way to more adventure.