How to fix E: Release file for URL is not valid yet (invalid for another Xd Xh Xmin Xs) in APT

First, verify that your system clock is actually incorrect:

date
timedatectl

The date command shows your system's current date/time. The timedatectl command shows time sync status and timezone info. If the date is clearly in the past (days, months, or even years ago), proceed to the next step.

On Windows, you can also check the actual current time as a reference point.

If your system clock is behind the hardware clock (common in WSL and VMs), synchronize them:

sudo hwclock --hctosys

The --hctosys flag means "hardware clock to system clock" — it reads the hardware clock (CMOS) and sets the system clock to match. If your hardware clock is correct, this instantly fixes the issue.

After running this command, verify the time changed:

date

If manual sync helped but you want to prevent future drift, enable automatic time synchronization:

sudo timedatectl set-ntp true

This enables Network Time Protocol (NTP), which automatically syncs your system clock with internet time servers. The status changes to "System clock synchronized: yes".

Verify it's active:

timedatectl

If NTP is available but not running, you may need to install an NTP client:

sudo apt update
sudo apt install systemd-timesyncd
sudo timedatectl set-ntp true

If your timezone is incorrect, set it to the right one:

timedatectl list-timezones          # List available timezones
sudo timedatectl set-timezone Asia/Kolkata  # Example: set to Indian time

Verify it was set:

timedatectl
date

After correcting timezone, verify it's UTC (Ubuntu's recommended default) for servers, or your local timezone for desktops.

Once your system time is correct, run:

sudo apt update

The error should now be gone. If it persists, there may be another issue (like a corrupted GPG key for a specific PPA). In that case, the error message will be more specific about which repository is problematic.

In Windows Subsystem for Linux (WSL), the system clock can drift after hibernation. To auto-sync on every startup, add this to your WSL distro's startup:

Create or edit /etc/wsl.conf:

[boot]
command = hwclock --hctosys

Alternatively, create a shell alias to sync manually whenever needed:

echo "alias fix-time='sudo hwclock --hctosys'" >> ~/.bashrc

Then use fix-time as needed.