Core 29.1 checks your computer’s clock against the median time it sees from peers. If the difference is large enough (about ten minutes or more) it will display a warning even if your desktop shows the correct date and time. The warning text in Core is: “Please check that your computer’s date and time are correct! If your clock is wrong, Bitcoin will not work properly.”
This happens when your system is not syncing correctly with a reliable time source. Common causes are NTP being disabled, your hardware clock being out of sync with your system clock (common in dual-boot or VM setups), or just clock drift if your computer hasn’t updated from the network recently.
The fix is to force your operating system to resync with a network time server. On Linux you can run timedatectl set-ntp true. On Windows you can run w32tm /resync. On macOS turn on “Set time automatically” in the Date & Time settings. If you are in a VM or dual-boot environment, check the hardware clock too and set it to UTC.
Once your system is syncing correctly, Core will realign with peers and the warning will go away after a few minutes or a restart.
