Where does the bug appear (feature/product)?
Background Agent (GitHub, Slack, Web, Linear)
Describe the Bug
I am writing to report a consistent build failure I am experiencing with a Background Agent using a Dockerfile.
Summary of the Issue:
The Docker build process fails during the RUN apt-get update step when executed as a Cursor Background Agent.
However, the exact same Dockerfile builds successfully on my local machine without any errors.
Error Details: The build log from the agent shows the following critical error:
E: Release file for http://security.ubuntu.com/ubuntu/dists/jammy-security/InRelease is not valid yet (invalid for another 1d 8h 29min 49s). Updates for this repository will not be applied.
E: Release file for http://archive.ubuntu.com/ubuntu/dists/jammy-updates/InRelease is not valid yet (invalid for another 1d 5h 25min 2s). Updates for this repository will not be applied.
E: Release file for http://archive.ubuntu.com/ubuntu/dists/jammy-backports/InRelease is not valid yet (invalid for another 1d 0h 13min 32s). Updates for this repository will not be applied.
ERROR: process "/bin/sh -c apt-get update..." did not complete successfully: exit code: 100
Steps to Reproduce
Since the build works locally, I believe the issue lies within the Cursor Background Agent’s execution environment. It seems the system time on the build host is incorrect, causing apt to reject the repository metadata files.
Replication Steps & Configuration: You should be able to replicate this issue using the following configuration:
{
"build": {
"dockerfile": "Dockerfile",
"context": "."
},
"terminals": [],
"agentCanUpdateSnapshot": true
}
FROM ubuntu:latest
RUN apt-get update --allow-releaseinfo-change --allow-unauthenticated && \
apt-get install -y --no-install-recommends \
bash \
curl \
git \
python3 \
python3-pip \
python3-venv \
ca-certificates \
unzip \
&& apt-get clean \
&& rm -rf /var/lib/apt/lists/* \
&& rm -rf /tmp/*
RUN git clone https://github.com/tfutils/tfenv.git /opt/tfenv && \
ln -s /opt/tfenv/bin/* /usr/local/bin
RUN curl -s https://raw.githubusercontent.com/terraform-linters/tflint/master/install_linux.sh | bash
RUN python3 -m venv /opt/checkov-venv && \
/opt/checkov-venv/bin/pip install --no-cache-dir checkov==3.2.413 && \
ln -s /opt/checkov-venv/bin/checkov /usr/local/bin/checkov
RUN tfenv install 1.12.2 && tfenv use 1.12.2
RUN groupadd -g 1000 terraform && \
useradd -m -s /bin/bash -u 1000 -g terraform terraform
WORKDIR /home/terraform
USER terraform
CMD ["/bin/bash"]
Could you please investigate the system time and time synchronization settings on your Background Agent build infrastructure?
Operating System
MacOS
Current Cursor Version (Menu → About Cursor → Copy)
Version: 1.6.0-dev.16
VSCode Version: 1.99.3
Commit: 0f4e1bbc86ec1d4e1df3291d00e1630ca8c30ee0
Date: 2025-08-26T08:18:39.043Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.5.0
Additional Information
I emailed support but haven’t received a reply, so I’m submitting this through the form.
Does this stop you from using Cursor
Yes - Cursor is unusable
