How to fix dpkg: error processing package (--configure): end of file on stdin at conffile prompt in APT

APTBEGINNERHIGH

This error occurs when dpkg attempts to ask about configuration file changes during package installation or upgrade in a non-interactive environment. Since stdin is empty or closed, the prompt cannot be answered and the operation fails.

What this error means

The "end of file on stdin at conffile prompt" error occurs when dpkg tries to prompt the user about how to handle configuration file changes, but cannot read user input because stdin is empty or closed. During package upgrades, dpkg may find that a configuration file (conffile) has been modified by the system administrator but also has a newer version in the package. dpkg asks the user whether to keep the existing version or use the new one. In non-interactive environments (Docker containers, CI/CD pipelines, automated scripts), this prompt blocks the operation and causes an EOF error. This is particularly common in Docker builds and automated update systems where the standard input stream is not connected to a terminal.

How to fix "dpkg: error processing package (--configure): end of file on stdin at conffile prompt"

1Use DEBIAN_FRONTEND=noninteractive for all apt commands

Set the DEBIAN_FRONTEND environment variable to suppress interactive prompts. This tells the Debian package system to make automatic decisions instead of prompting:

bash

export DEBIAN_FRONTEND=noninteractive
apt-get update
apt-get upgrade -y

In Docker, add this to your Dockerfile:

dockerfile

ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update && apt-get upgrade -y

Or use it inline for a single command:

bash

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

2Add dpkg force options to handle configuration files

Use dpkg options to automatically decide how to handle conflicting configuration files:

bash

# Use --force-confold to keep the existing configuration file
apt-get upgrade -y -o Dpkg::Options::="--force-confold"

# Use --force-confnew to use the new configuration file from the package
apt-get upgrade -y -o Dpkg::Options::="--force-confnew"

# Use --force-confdef to use the default action (usually keep old)
apt-get upgrade -y -o Dpkg::Options::="--force-confdef"

Combine multiple options for robustness:

bash

apt-get upgrade -y \
  -o Dpkg::Options::="--force-confdef" \
  -o Dpkg::Options::="--force-confold"

3Combine DEBIAN_FRONTEND and dpkg options together

For the most reliable non-interactive upgrades, use both methods together:

bash

export DEBIAN_FRONTEND=noninteractive
apt-get update
apt-get upgrade -y \
  -o Dpkg::Options::="--force-confdef" \
  -o Dpkg::Options::="--force-confold"

This approach handles both the interactive prompts from apt and the conffile prompts from dpkg.

4Use dpkg --configure -a to fix interrupted installations

If dpkg was interrupted mid-installation, you may see a message to run dpkg --configure -a. Use it with the same non-interactive approach:

bash

# Fix interrupted packages
export DEBIAN_FRONTEND=noninteractive
dpkg --configure -a \
  --apt \
  --force-confdef \
  --force-confold

Or with apt:

bash

DEBIAN_FRONTEND=noninteractive apt-get install -f \
  -o Dpkg::Options::="--force-confdef" \
  -o Dpkg::Options::="--force-confold"

5Redirect stdin from /dev/null as a fallback

If the above methods don't work, redirect stdin from /dev/null or provide empty input:

bash

# Redirect from /dev/null
apt-get upgrade -y < /dev/null

# Or feed empty lines
yes '' | apt-get upgrade -y

# For dpkg directly
dpkg --configure -a < /dev/null

This ensures stdin is closed cleanly rather than left open waiting for input.

How to fix dpkg: error processing package (--configure): end of file on stdin at conffile prompt in APT

What this error means

Typical symptoms

Common causes

How to fix "dpkg: error processing package (--configure): end of file on stdin at conffile prompt"

Advanced notes

Related errors

Official resources & further reading