Unable to replace USB stick from boot pool

[Steasenburger]

Hi everyone,
One of my USB sticks that I used as a mirrored boot pool has failed, and I now want to replace it with an (Sata M2) SSD inside a USB enclosing.
I tried to do this via the GUI by clicking on the three dots menu for the drive that failed (Status "unavail") and selected the new drive, but the following error message occurs:

Error: [EZFS_BADTARGET] cannot replace 17657486509029781977 with /dev/sdf3: already in replacing/spare config; wait for completion or use 'zpool detach'

Unfortunately, I wasn't able to solve this myself, because most of the threads that I found had another root issue or were dealing with TrueNAS Core and not SCALE.
Any idea how I could solve this?

Best wishes

Here is the output of zpool status, if it helps:

Code:

root@truenas:~# zpool status
  pool: freenas-boot
 state: DEGRADED
status: One or more devices could not be used because the label is missing or
        invalid.  Sufficient replicas exist for the pool to continue
        functioning in a degraded state.
action: Replace the device using 'zpool replace'.
   see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-4J
  scan: scrub repaired 0B in 00:02:23 with 0 errors on Sun May 21 03:47:24 2023
config:

        NAME                      STATE     READ WRITE CKSUM
        freenas-boot              DEGRADED     0     0     0
          mirror-0                DEGRADED     0     0     0
            17657486509029781977  UNAVAIL      0     0     0  was /dev/sdf2
            sde2                  ONLINE       0     0   186

errors: No known data errors

  pool: hdd
 state: ONLINE
  scan: scrub repaired 0B in 04:10:54 with 0 errors on Tue May 23 05:10:56 2023
config:

        NAME                                      STATE     READ WRITE CKSUM
        hdd                                       ONLINE       0     0     0
          raidz1-0                                ONLINE       0     0     0
            530d22d3-95cc-11ed-addb-001b228132e0  ONLINE       0     0     0
            c55bd61f-27f2-11ea-a1a6-40b07609074b  ONLINE       0     0     0
            9eb90152-7c01-11ea-bfb9-40b07609074b  ONLINE       0     0     0
            c91d0cbd-27f2-11ea-a1a6-40b07609074b  ONLINE       0     0     0

errors: No known data errors

  pool: ssd
 state: ONLINE
  scan: scrub repaired 0B in 00:00:08 with 0 errors on Mon May  8 01:00:09 2023
config:

        NAME                                    STATE     READ WRITE CKSUM
        ssd                                     ONLINE       0     0     0
          e29055a8-270f-11ea-88d3-40b07609074b  ONLINE       0     0     0

errors: No known data errors