The update to 18.04 LTS is hung in the read cache

I'm trying to update Ubuntu 16.04 to 18.04, but it hangs in "Read cache":

$ sudo do-release-upgrade
Searching for a new version of Ubuntu
Get: 1 Signature of update tool [819 B]                                                                                                                                                                       
Get: 2 update tool [1,246 kB]                                                                                                                                                                              
Fetched 1,247 kB in 0s (0 B / s)
authenticate & # 39; bionic.tar.gz & # 39; against & bionic.tar.gz.gpg & # 39;
extracting & # 39; bionic.tar.gz & # 39;

Read cache

The cursor sits blinking. Any ideas of what is wrong?