My adoptable storage is full. How can I move the data to a bigger MicroSD card?
Having a similar issue, I read through the comments to your question and ended up doing the following based on a hint suggested by Barleyman:


Go to Settings > Storage &amp; USB › Internal Storage, click on "Migrate data" to move your data back to internal


In case you do not have enough space left on internal to move everything back (which was my case), here are some additionnal steps:


Connect the phone to a PC via USB and back-up the contents of the old "adopted" SD Card
Manually delete enough data from the old SD Card to be able to do the move: typically pictures and videos that you can easily restore afterwards
Click on "Migrate data" in  Settings > Storage &amp; USB › Internal Storage
Check that the old "adopted" SD Card is now empty (or even format it back to "Portable") then eject it
Insert the new SD Card and set it up as "Internal storage" and agree to move the data to it
Eventually reconnect the phone to the PC via USB to restore manually deleted data




Reference: Answer to "How does the "Format as internal storage" feature work in Android 6.0+?":


  
  You can reverse the process by opening "internal storage" from storage settings and there's "migrate data" that will copy everything back to internal nvram.