I configured an LVM Backend and tried this out and this worked fine for me.

cinder show 3f83570d-b1a0-4c91-9773-2b697c1e982d

+--------------------------------+--------------------------------------+
| Property                       | Value                                |
+--------------------------------+--------------------------------------+
| attached_servers               | []                                   |
| attachment_ids                 | []                                   |
| availability_zone              | nova                                 |
| bootable                       | false                                |
| consistencygroup_id            | None                                 |
| created_at                     | 2019-08-02T08:17:09.000000           |
| description                    | None                                 |
| encrypted                      | True                                 |
| id                             | 3f83570d-b1a0-4c91-9773-2b697c1e982d |
| metadata                       |                                      |
| migration_status               | success                              |
| multiattach                    | False                                |
| name                           | encrypted volume                     |
| os-vol-host-attr:host          | infra@lvmdriver-1#lvmdriver-1        |
| os-vol-mig-status-attr:migstat | success                              |
| os-vol-mig-status-attr:name_id | e9b415df-1ec7-4e41-a7c8-d9f4c8a39ba5 |
| os-vol-tenant-attr:tenant_id   | 5cb1426e43cd4f2db6bb428a6051622a     |
| replication_status             | None                                 |
| size                           | 1                                    |
| snapshot_id                    | None                                 |
| source_volid                   | None                                 |
| status                         | available                            |
| updated_at                     | 2019-08-02T09:56:23.000000           |
| user_id                        | d645bb574c394feeb2390140ed981f8c     |
| volume_type                    | LUKS                                 |
+--------------------------------+--------------------------------------+

I executed the command 

cinder migrate --force-host-copy True 3f83570d-b1a0-4c91-9773-2b697c1e982d infra@lvmdriver-3
Request to migrate volume 3f83570d-b1a0-4c91-9773-2b697c1e982d has been accepted.

After the command.. I got

cinder show 3f83570d-b1a0-4c91-9773-2b697c1e982d
+--------------------------------+--------------------------------------+
| Property                       | Value                                |
+--------------------------------+--------------------------------------+
| attached_servers               | []                                   |
| attachment_ids                 | []                                   |
| availability_zone              | nova                                 |
| bootable                       | false                                |
| consistencygroup_id            | None                                 |
| created_at                     | 2019-08-02T08:17:09.000000           |
| description                    | None                                 |
| encrypted                      | True                                 |
| id                             | 3f83570d-b1a0-4c91-9773-2b697c1e982d |
| metadata                       |                                      |
| migration_status               | success                              |
| multiattach                    | False                                |
| name                           | encrypted volume                     |
| os-vol-host-attr:host          | infra@lvmdriver-3#lvmdriver-1        |
| os-vol-mig-status-attr:migstat | success                              |
| os-vol-mig-status-attr:name_id | None                                 |
| os-vol-tenant-attr:tenant_id   | 5cb1426e43cd4f2db6bb428a6051622a     |
| replication_status             | None                                 |
| size                           | 1                                    |
| snapshot_id                    | None                                 |
| source_volid                   | None                                 |
| status                         | available                            |
| updated_at                     | 2019-08-02T10:15:17.000000           |
| user_id                        | d645bb574c394feeb2390140ed981f8c     |
| volume_type                    | LUKS                                 |
+--------------------------------+--------------------------------------+


Can you explain why os-vol-mig-status-attr:migstat | error | occured.

I'm new here..So please help me in finding the solution.!