Server stop working - lmdb index error

Hi All
When I try to start server, its log contains the error:

2021-02-08 15:53:58: WARNING: Creating file entry index. This might take a while…
2021-02-08 15:54:01: ERROR: LMDB: Failed to put data (MDB_KEYEXIST: Key/data pair already exists)
2021-02-08 15:54:01: ERROR: LMDB error after putting element. Error state interrupting…
2021-02-08 15:54:01: ERROR: Setting up file index failed
2021-02-08 15:54:01: ERROR: Could not create or open file entry index. Exiting.
/var/log/urbackup.log (END)

Is there any standard tools for lmdb repairing? Or any server hacks
for this?

Server v2.4.13 on Ubuntu 18.04.5 (ext4)
repair-database and other CLI options was not any result.