Sometimes when you install the update package or Opengapps package, you can see the message.
To solve this problem, you have to redownload packages.
Before redownloading, you can check the package file.

When you update android, you can check file's checksum via md5sum command.

both

$ md5sum updatepackage-odroidc2-eng-s905_6.0.1_master-65.zip
da61b169242938816f8346627bc088d5  updatepackage-odroidc2-eng-s905_6.0.1_master-65.zip
 
$ cat updatepackage-odroidc2-eng-s905_6.0.1_master-65.zip.md5sum
da61b169242938816f8346627bc088d5  updatepackage-odroidc2-eng-s905_6.0.1_master-65.zip

If result value is different, please redownload it.