Large logs don't appear in Airflow 3.1.2

[gvergnolle]

Apache Airflow version

3.1.2

If "Other Airflow 2/3 version" selected, which one?

None

What happened?

When the logs are of size ~100 lines, the log window is "cropped". As a result, we can't see logs properly:

• Logs don't expand on the full log component
• Depending on the size of the logs, the logs window either gets reduced or completely disappears. When it's reduced, we can't scroll to the top line.

The logs exist: I can download them or inspect them in the HTML, but the container is not visible from a user's POV.

The issue appeared on both Mozilla Firefox and Chrome, so I believe it's not related to the browser used.

This behaviour happened with the recent introduction of 3.1.2, I didn't observe it with the previous minor version 3.1.1.

What you think should happen instead?

We can normally scroll through the logs of a task, regardless of the size.

How to reproduce

Here's a simple DAG:

import logging
import pendulum
from airflow.sdk import (
    task,
    DAG,
)

logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

N_LOGS = 100

with DAG(
    dag_id="test_dag",
    schedule=None,
    start_date=pendulum.datetime(2025, 1, 1, tz="UTC"),
    max_active_runs=1,
    is_paused_upon_creation=False,
) as dag:

    @task(dag=dag, task_id="print_stuff")
    def print_stuff():
        for i in range(N_LOGS):
            logger.info(f"Processing item {i}")

    print_stuff()

Try it with N_LOGS=100, and the window is significantly reduced. We can't scroll to the first line (see video attached)

Screen.Recording.2025-11-05.at.3.10.24.PM.mov

Try it with N_LOGS=1000, and all logs completely disappear (see screenshot). I am scrolling in the void, and I can't make the logs appear.

ADDENDUM: The size of the browser window also directly impacts the rendering of the logs.

Operating System

Debian GNU/Linux 12 (bookworm)

Versions of Apache Airflow Providers

apache-airflow-providers-standard==1.9.1

Deployment

Docker-Compose

Deployment details

No response

Anything else?

I have observed the same behaviour with an EcsRunTaskOperator, so it may affect all operator types, making it a significant issue.

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[r-richmond]

We are also experiencing this on 3.1.2. It was not present on 3.1.1.

A few other findings we had.

• wrapping text and unwrapping it causes the text to overlap
• if you make the vertical height of the window much larger or smaller you can change wether or not the logs disappear entirely or are just somewhat blocked from displaying.

[vatsrahul1001]

Yeah PR regressed logs. We have reverted this in main with PR already. Unwrapping the logs should help