When i want to upgrade my system it show me this.

**393 upgraded, 473 newly installed, 130 to remove and 1486 not upgraded.
4 not fully installed or removed.
Need to get 0 B/607 MB of archives.
After this operation, 1,197 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Reading changelogs… Done
Extracting templates from packages: 100%
Preconfiguring packages …
dpkg: considering deconfiguration of systemd, which would be broken by installation of libc6:amd64 …
dpkg: yes, will deconfigure systemd (broken by libc6:amd64)
(Reading database … 319760 files and directories currently installed.)
Preparing to unpack …/libc6_2.40-2_amd64.deb …
De-configuring systemd (235-2) …
Checking for services that may need to be restarted…
Checking init scripts…

The current installation does not have a merged-/usr layout.
This is unsupported and unpacking libc6 would break the system.
Refusing to unpack. Please install the usrmerge package and try again.

dpkg: error processing archive /var/cache/apt/archives/libc6_2.40-2_amd64.deb (–unpack):
new libc6:amd64 package pre-installation script subprocess returned error exit status 1
dpkg: warning: version ‘in-favour’ has bad syntax: version number does not start with digit
dpkg: warning: version ‘in-favour’ has bad syntax: version number does not start with digit
Errors were encountered while processing:
/var/cache/apt/archives/libc6_2.40-2_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
**

any solution to this problem