My better half has a Sony Xperia M4 Aqua with 8GB* internal storage, she is constantly getting notifications that the phone apps are out of date but there is not enough storage on the flash memory to update the apps.
Yes I had this exact phone, A phone so inadequate that it didn’t have the storage to install its own updates, yet FULL of useless crap from Sony. Also, the bootloader on mine was locked down so phone couldn’t be rooted to get rid of the bloatware and install a slimmed-down ROM.
I had everything set to use SD card (photos, docs and every possible app) and cleared out cached data regularly. It made little practical difference. I had to run minimal apps, and nothing storage-hungry. No Pinterest, no games, etc. If I wanted to install a new app, or run updates, I would have to delete an app first, then try to reinstall it later.
Absolute joke of a phone.
In the end I bit the bullet and bought myself a proper phone that actually works. I was going to keep the M4 as a “spare” to take out on my bike etc, but in reality I never have, and, now you have reminded me, will probably cut it in half with an angle grinder today 🙂