Raid5, deleted a device, now see "some devices missing"

Raid5, deleted a device, now see "some devices missing"

[Tyler Hardin]

I replace a drive the dumb way by adding a new one and deleting the
old. The add worked fine and the delete seemed to work, the change in
disk usage moved from the old drive to the new drive, but when I try
to mount the fs I now get an error.

$ uname -a
Linux lnv 5.8.0-3-amd64 #1 SMP Debian 5.8.14-1 (2020-10-10) x86_64 GNU/Linux

$ btrfs --version
btrfs-progs v5.7

$ sudo btrfs fi show
Label: none  uuid: 5cf68b2e-3665-41aa-a38d-6e616e52d4d7
Total devices 1 FS bytes used 1.52TiB
devid    1 size 1.79TiB used 1.53TiB path /dev/sda3

Label: none  uuid: 8e6f0b0f-8b93-4fda-a243-8ed2d798bfd7
Total devices 5 FS bytes used 4.56TiB
devid    1 size 1.82TiB used 1.52TiB path /dev/sdc
devid    2 size 1.82TiB used 1.52TiB path /dev/sdd
devid    3 size 1.82TiB used 1.52TiB path /dev/sde
devid    5 size 7.28TiB used 1.52TiB path /dev/sdb
*** Some devices missing

$ sudo mount /dev/sdb /mnt/data
mount: /mnt/data: wrong fs type, bad option, bad superblock on
/dev/sdb, missing codepage or helper program, or other error.

$ dmesg
[ 1130.412726] BTRFS info (device sdc): disk space caching is enabled
[ 1130.412731] BTRFS info (device sdc): has skinny extents
[ 1130.483868] BTRFS error (device sdc): super_num_devices 5 mismatch
with num_devices 4 found here
[ 1130.483877] BTRFS error (device sdc): failed to read chunk tree: -22
[ 1130.503239] BTRFS error (device sdc): open_ctree failed

Thanks in advance.