You need to determine first which volume is read-only. UBIFS will switch to read-only to protect itself when an issue is discovered. Check the volume status:
If it's the JFFS2 volume as most likely, then it's recoverable, although not simple. You would basically need to reformat that volume (or possibly recreate it which is what someone did in that other thread). The opration carries a high risk of bricking the router, so that might be considered only as a last ressort option.
There is a ubiformat command included in the firmware, but since I have never used it myself, I'm not ready to blindly tell you to run it and possibly brick everything. Let's start first by confirming that it's a UBI volume that's in a non-OK state, and which one.
UBI version: 1
Count of UBI devices: 1
UBI control device major/minor: 10:59
Present UBI devices: ubi0
ubi0
Volumes count: 8
Logical eraseblock size: 126976 bytes, 124.0 KiB
Total amount of logical eraseblocks: 1638 (207986688 bytes, 198.3 MiB)
Amount of available logical eraseblocks: 309 (39235584 bytes, 37.4 MiB)
Maximum count of volumes 128
Count of bad physical eraseblocks: 378
Count of reserved physical eraseblocks: 0
Current maximum erase counter value: 1894
Minimum input/output unit size: 2048 bytes
Character device major/minor: 249:0
Present volumes: 1, 2, 3, 4, 5, 6, 10, 11
Volume ID: 1 (on ubi0)
Type: static
Alignment: 1
Size: 1 LEBs (126976 bytes, 124.0 KiB)
Data bytes: 1280 bytes (1.2 KiB)
State: OK
Name: metadata1
Character device major/minor: 249:2
-----------------------------------
Volume ID: 2 (on ubi0)
Type: static
Alignment: 1
Size: 1 LEBs (126976 bytes, 124.0 KiB)
Data bytes: 1280 bytes (1.2 KiB)
State: OK
Name: metadata2
Character device major/minor: 249:3
-----------------------------------
Volume ID: 3 (on ubi0)
Type: static
Alignment: 1
Size: 94 LEBs (11935744 bytes, 11.3 MiB)
Data bytes: 10806988 bytes (10.3 MiB)
State: OK
Name: bootfs1
Character device major/minor: 249:4
-----------------------------------
Volume ID: 4 (on ubi0)
Type: dynamic
Alignment: 1
Size: 463 LEBs (58789888 bytes, 56.0 MiB)
State: OK
Name: rootfs1
Character device major/minor: 249:5
-----------------------------------
Volume ID: 5 (on ubi0)
Type: static
Alignment: 1
Size: 93 LEBs (11808768 bytes, 11.2 MiB)
Data bytes: 10697784 bytes (10.2 MiB)
State: OK
Name: bootfs2
Character device major/minor: 249:6
-----------------------------------
Volume ID: 6 (on ubi0)
Type: dynamic
Alignment: 1
Size: 440 LEBs (55869440 bytes, 53.2 MiB)
State: OK
Name: rootfs2
Character device major/minor: 249:7
-----------------------------------
-----------------------------------
-----------------------------------
-----------------------------------
Volume ID: 10 (on ubi0)
Type: dynamic
Alignment: 1
Size: 166 LEBs (21078016 bytes, 20.1 MiB)
State: OK
Name: data
Character device major/minor: 249:11
-----------------------------------
Volume ID: 11 (on ubi0)
Type: dynamic
Alignment: 1
Size: 67 LEBs (8507392 bytes, 8.1 MiB)
State: OK
Name: defaults
Character device major/minor: 249:12
just got my ax6000 today, installing merlin and got low jffs error and cant use vpn service.
strange thing is my volume 13 is missing (volume count should be 9 not 8)
does my router is defective?
LOG:
Aug 22 23:49:05 dropbear: JFFS unwritable - creating temporary keys in RAM