I know that there are quite a few users like myself who are running into a very annoying issue, it's called the "INSUFFICIENT STORAGE SPACE" error on our OPPO devices. So I looked into a very easy fix.
This error happens when the original APP partition in our internal memory is filled (2.90 GB size on my phone, out of the 32 GB), thus it doesn't allow for any additional app downloads or installations.
This procedure doesn't require scripting or too much tampering with the internal system of the phone, instead, it just (1) requires root permission, a (2) SD card, $2.50 (I think) in your play store account, and (3) a computer.
Here are the instructions:
** As always, don't just be a leech, show some support by giving THANKS **
1) Make sure you have root access, and a software program called "Minitool" installed on your computer. I did this on Windows 7. (Download here)
2) your SD card should be in the format of "Fat32" or "Exfat" originally. If not, make sure that your PC (Windows) can detect the drive (SD card) on your computer.
3) On your phone, download an app called Link2SD and also get the paid version (this is required because it gives your phone the ability to insert a script onto your internal memory that allows it to "link" to the SD external memory.)
4) Plug in your external SD card into your computer, how I did this was through a adapter.
5) Now boot up Minitool on your PC, and you should see your external sd card drive and also your other hard drives are connected to your PC.
6) "Remove" or "Delete" the partition that is currently on your SD card. MAKE SURE TO BACKUP THE FILES ON YOUR SD CARD first before you remove the partition.
7) Now create a partition and set your desired size, followed by the format of Fat32 and make sure it is a "Primary" partition not "Logic/Logical".
(This partition will be your external memory)
8) Next, create another partition with the rest of the memory left over in the SD card, and have that format as Ext4. Make sure it is a "primary" as well.
(This partition will be your linked APP memory, aka your Second Partition)
9) Click on "apply" when everything looks right, the button is located on the top left of the program. Let it run its course.
10) There you go! Once you exit the program, eject the SD card and plug it back into your phone, you will have your phone detect a smaller sized Fat32 external SD card, because the other partition (possibly hidden) is the Ext4.
11) Go into the Link2SD app which should be running the paid "Plus" version now. And follow the instructions, it should do everything for you.
12) Once rebooted, you will be able to download more apps now! In the beginning it may be a tiny bit glitchy because the script might still not be picked up by Link2SD. May sure you have given root permission to the app.
13) CONGRATS! You are now done! If you ever find yourself downloading large apps that require storage space again, LINK that app'a information and data (through Link2SD) to the SD card by hitting "Create Link", then checkmark all the app files associated with the large app.
* * NOTES * *
- If your Link2SD doesn't pick up a difference in your SD card, click on the left menu and select "Recreate Mount Scripts". See what it says, and if there are any errors on your SD card.
- Your SD card should be of at least class 6 and above. I used a class 10 SD card and there were absolutely no speed issues (lag) with the apps.
- This method will work on MANY other Android phones, as long as it can read your SD card and as long as the script is properly installed.
Again, HIT THANKS if this helped you in any way!