While updating Ubuntu with sudo apt-get update, I get the following error:
Error: 6 http://packages.ros.org/ros/ubuntu bionic InRelease
The following signatures could not be verified because there is no public key: NO_PUBKEY F42ED6FBAB17C654
Getting: 11 https://dl.winehq.org/wine-builds/ubuntu bionic/ main i386 Packages [1,068 kB]
Fetching: 12 https://dl.winehq.org/wine-builds/ubuntu bionic/main amd64 Packages [1,032 kB]
Reading package list... done
W: GPG error: http ://packages.ros.org/ros/ubuntu bionic InRelease: The following signatures could not be verified because there is no public key: NO_PUBKEY F42ED6FBAB17C654
E: Repository "http://packages.ros.org/ros/ubuntu bionic InRelease" does not have a digital signature .
N: The source cannot be safely updated, so it is disabled by default.
N: See the apt-secure(8) manual for details on repository creation and user configuration.
The reason is that there is no public key locally. The solution is as follows:
Step1: Open the OpenPGP Keyserver
Step2: Copy and search F42ED6FBAB17C654 of NO_PUBKEY F42ED6FBAB17C654 in the above question
stem3: Find the option corresponding to the public key and open it, such as my option is
self self f42ed6fbab17c654 2021-05-29T05:59:45Z 2025-06-01T05:59:45Z ____________________ [ selfsig]
After opening it is as follows:
-----BEGIN PGP PUBLIC KEY BLOCK----- Comment: Hostname: Version: Hockeypuck 2.1.0-189-g15ebf24 xsFNBFzvJpYBEADY8l1YvO7iYW5gUESyzsTGnMvVUmlV3XarBaJz9bGRmgPXh7jc VFrQhE0L/HV7LOfoLI9H2GWYyHBqN5ERBlcA8XxG3ZvX7t9nAZPQT2Xxe3GT3tro u5oCR+SyHN9xPnUwDuqUSvJ2eqMYb9B/Hph3OmtjG30jSNq9kOF5bBTk1hOTGPH4 K/AY0jzT6OpHfXU6ytlFsI47ZKsnTUhipGsKucQ1CXlyirndZ3V3k70YaooZ55rG aIoAWlx2H0J7sAHmqS29N9jV9mo135d+d+TdLBXI0PXtiHzE9IPaX+ctdSUrPnp+ TwR99lxglpIG6hLuvOMAaxiqFBB/Jf3XJ8OBakfS6nHrWH2WqQxRbiITl0irkQoz pwNEF2Bv0+Jvs1UFEdVGz5a8xexQHst/RmKrtHLct3iOCvBNqoAQRbvWvBhPjO/p V5cYeUljZ5wpHyFkaEViClaVWqa6PIsyLqmyjsruPCWlURLsQoQxABcL8bwxX7UT hM6CtH6tGlYZ85RIzRifIm2oudzV5l+8oRgFr9yVcwyOFT6JCioqkwldW52P1pk/ /SnuexC6LYqqDuHUs5NnokzzpfS6QaWfTY5P5tz4KHJfsjDIktly3mKVfY0fSPVV okdGpcUzvz2hq1fqjxB6MlB/1vtk0bImfcsoxBmF7H+4E9ZN1sX/tSb0KKARAQAB zSZPcGVuIFJvYm90aWNzIDxpbmZvQG9zcmZvdW5kYXRpb24ub3JnPsLBlAQTAQgA PgIbAwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBMHPbjHmut6IaLFytPQu1vur F8ZUBQJgsdhRBQkLTMW7AAoJEPQu1vurF8ZUTMwP/3f7EkOPIFjUdRmpNJ2db4iB RQu5b2SJRG+KIdbvQBzKUBMV6/RUhEDPjhXZI3zDevzBewvAMKkqs2Q1cWo9WV7Z PyTkvSyey/Tjn+PozcdvzkvrEjDMftIk8E1WzLGq7vnPLZ1q/b6Vq4H373Z+EDWa DaDwW72CbCBLWAVtqff80CwlI2x8fYHKr3VBUnwcXNHR4+nRABfAWnaU4k+oTshC Qucsd8vitNfsSXrKuKyz91IRHRPnJjx8UvGU4tRGfrHkw1505EZvgP02vXeRyWBR fKiL1vGy4tCSRDdZO3ms2J2m08VPv65HsHaWYMnO+rNJmMZj9d9JdL/9GRf5F6U0 quoIFL39BhUEvBynuqlrqistnyOhw8W/IQy/ymNzBMcMz6rcMjMwhkgm/LNXoSD1 1OrJu4ktQwRhwvGVarnB8ihwjsTxZFylaLmFSfaA+OAlOqCLS1OkIVMzjW+Ul6A6 qjiCEUOsnlf4CGlhzNMZOx3low6ixzEqKOcfECpeIj80a2fBDmWkcAAjlHu6VBhA TUDG9e2xKLzV2Z/DLYsb3+n9QW7KO0yZKfiuUo6AYboAioQKn5jh3iRvjGh2Ujpo 22G+oae3PcCc7G+z12j6xIY709FQuA49dA2YpzMda0/OX4LP56STEveDRrO+CnV6 WE+F5FaIKwb72PL4rLi4wsGUBBMBCgA+FiEEwc9uMea63ohosXK09C7W+6sXxlQF AlzvJpYCGwMFCQPCZwAFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AACgkQ9C7W+6sX xlSSEg/9FtljUSu8IRTLyIsmb1pKktCcNmXnEgs7HJmXOmD4yXltvQSRAOv3Z+gK By8t4A0oBE0JoYvI0haS7IOi89XTFkmsTLSSAGsM1vf742Z0j/4YD3amR50xdeKh C+p2zFRqBcAgH+w0YHIkSGzfsXTkCcW9luNSFx6rfFOW8AxysFauAHg3AGK9ljoi Au+X8JFClVjAA1KEhB1u8e9lLFGidaE1evq/9Zx/yuynuDZWonY3YBxZPzhpr0Et Dc579KCs3HhASEDXLutzehqo9W7llc4r7g7XgmulsRndez1gSOtw64QMSliS0Dyq pQNN0XJmvFv1LoGq5QqsDqNmBP3XeSMnh7tgBmhsLisfTDi7Q+uoOBg6RcD0yjsv rTX/tloMmhvzRRwr5nXZlLDvciAGLHoOIlV9e5aSTk8zbOwWfpQ5BdQ2VmUMA6Pk 0LTVXR8nw/S/oY71g5JJDHSPlS2RRtF+n/hbu4I8W/ABq1YQcmGUzexA2Iw1K0kV 6CvnrFC7Vr9xskfsZ1ux4yEb9/QFopCpcIjd98HnLkA4tz0fDs9iJMVCy5jV49GE T4n2Z6OBZFnGSMAf8WUC5upeQOC16sKH6wuTMZ/6bLYhuwwK5z7dp40wnkSP++Vd 58If8yk9YAcKqlCF7YMRP+NFJozndRIAc3HyTDgw9STETGAjtJ0= =bJcS -----END PGP PUBLIC KEY BLOCK-----
Step4: Create a file in a folder, regardless of the type, directly open the terminal and enter touch public_key. Then gedit public_key. Finally, copy a large number of things in Step3.
Step5: Use sudo apt-key add <filename>, for example, this time, I enter sudo apt-key add public_key
Step6: Execute sudo apt-get update