How to fix debconf: (No usable dialog-like program is installed) in APT

The simplest fix is to install one of the dialog-like programs that debconf needs. Run:

sudo apt-get update
sudo apt-get install -y dialog

Alternatively, you can install whiptail instead:

sudo apt-get update
sudo apt-get install -y whiptail

Both provide the dialog frontend that debconf requires. Dialog is more feature-complete, while whiptail is lighter-weight.

If you're building Docker images or running automated installations where interactive prompts are not needed or desired, set the DEBIAN_FRONTEND environment variable to noninteractive:

# In your Dockerfile
ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update && apt-get install -y your-package

Or set it per command:

DEBIAN_FRONTEND=noninteractive apt-get install -y your-package

This tells debconf to skip the dialog frontend entirely and use non-interactive configuration. This is the preferred approach for automated deployments since no interactive prompts are possible in containers anyway.

If you want to minimize image size in Docker while avoiding this error, use:

RUN apt-get update && apt-get install -y --no-install-recommends dialog && rm -rf /var/lib/apt/lists/*

Then set DEBIAN_FRONTEND=noninteractive for subsequent installations. The --no-install-recommends flag prevents unnecessary dependencies from being installed, and the rm command cleans up apt cache to reduce image size.

To verify that debconf is now properly configured, run:

dpkg-reconfigure -f noninteractive tzdata

This should complete without the "No usable dialog-like program" error. If you see no errors, debconf is now properly configured.