Hello, I ran btrfsck on my volume with the repair option. When I re-run it, I get the same errors as before. Attached you find the output of btrfsck in repair-mode. Are these errors, that btrfsck cannot fix? Regards, Hendrik Below some samples: Extent back ref already exists for 2994950590464 parent 863072366592 root 0 ref mismatch on [32935936 4096] extent item 1, found 2 repair deleting extent record: key 32935936 168 4096 adding new tree backref on start 32935936 len 4096 parent 2994784206848 root 2994784206848 Incorrect global backref count on 32935936 found 1 wanted 2 backpointer mismatch on [32935936 4096] ref mismatch on [32997376 4096] extent item 1, found 2 repair deleting extent record: key 32997376 168 4096 adding new tree backref on start 32997376 len 4096 parent 2994824708096 root 2994824708096 Incorrect global backref count on 32997376 found 1 wanted 2 backpointer mismatch on [32997376 4096] Incorrect global backref count on 8988365651968 found 1 wanted 0 backpointer mismatch on [8988365651968 4096] repaired damaged extent references checking free space cache checking fs roots root 256 inode 9579 errors 100, file extent discount root 256 inode 9580 errors 100, file extent discount root 256 inode 14258 errors 100, file extent discount root 256 inode 14259 errors 100, file extent discount root 4444 inode 9579 errors 100, file extent discount root 4444 inode 9580 errors 100, file extent discount root 4444 inode 14258 errors 100, file extent discount root 4444 inode 14259 errors 100, file extent discount enabling repair mode Checking filesystem on /dev/sdc1 UUID: 989306aa-d291-4752-8477-0baf94f8c42f cache and super generation don't match, space cache will be invalidated found 827360733827 bytes used err is 1 total csum bytes: 4446455380 total tree bytes: 5506977792 total fs tree bytes: 137293824 total extent tree bytes: 258691072 btree space waste bytes: 496921489 file data blocks allocated: 6440132583424 referenced 6424163344384 Btrfs v3.12