# 10. Troubleshooting¶

The following shows some of the most frequently seen errors and their solutions for quick reference. For other issues that happened during the installation, upgrading or later usage, you may seek Technical support by submitting a bug report to PicoScenes Issues Tracker.

## 10.1. Errors during installation & daily update¶

• Problem: Error during apt update, “Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. XXX…. The repository ‘xxxx’ does not have a Release file.”

Solution: Re-install ca-certificate package by sudo apt-get install --reinstall ca-certificates.

• Problem: Error during apt installation saying, “E: fail to fetch XXX, File has unexpected size (xxx != xxx). …”

Solution: The possible reason is that the PicoScenes repository is updated, but your local apt cache is not synced. To fix this error, you should run sudo apt update to sync your local apt cache. If you still encounter this problem, you may seek Technical support.

• Problem: Current PicoScenes build is expired. You should upgrade PicoScenes to the latest version.

Solution: As PicoScenes is still under active development, we set a 15-day expiration for each PicoScenes build, the installed binary program. If your current build is expired, you have two ways to upgrade it.

The first is the normal and easy Debian “sudo apt update && sudo apt upgrade” approach. However, if you encounter errors during the first approach, you may completely uninstall PicoScenes by “sudo apt remove picoscenes-driver-xxxxxx” and then re-install PicoScenes again.

## 10.2. Runtime errors¶

• Problem: [Warning] Incompatible kernel version, current version: XXX, expected version: YYY.

Solution: This is because your system loads the incompatible kernel. Solution: reboot your computer and choose the expected kernel version YYY in grub menu.

If your computer doesn’t show the grub boot selection menu, you may refer to https://askubuntu.com/questions/16042/how-to-get-to-the-grub-menu-at-boot-time/16049#16049 to restore the menu.

• Problem: PicoScenes requires your system clock to be synchronous with a global NTP server.

Solution: This error usually happens when you connect to a AP but it has no internet connection and with wrong clock/time setting. You may either switch to an internet-connected AP or configure the AP’s clock/time setting manually.

• Problem: Error during USRP B200 series installation, “Could not find the image ‘usrp_b200_fw.hex’ in the image directory /usr/share/uhd/images ….”

Solution: run sudo /usr/lib/uhd/utils/uhd_images_downloader.py to download all USRP images.