Seq 2025.2 Release

Nicholas Blumhardt -

TL;DR: Seq 2025.2 is ready on datalust.co and as datalust/seq in your Docker container registry of choice.

A number of improvements were in-flight during the recent Seq 2025.1 release, but came in too late for the final cut-off date. Today's release, Seq 2025.2, rolls up these small bug fixes and feature additions.

If you automate deployment of Seq in your organization (or dev environment), note that newly-provisioned Seq 2025.2 instances will require an explicit opt-out of authentication if no administrator password is specified. Read on below for the details of this change.

What's new in 2025.2?

The release milestone includes:

  • Alert cloning: complex alerts can take some time to configure. Get a head start by cloning an existing alert, using the "Clone" button at the bottom of the alert edit form.
  • Require a password, or opt-out, when initializing a new instance: to protect from various failure modes related to instance/container storage, a password or expclit opt-out is required when initializing new Seq instances (see "Breaking changes" below).
  • From now/to now keyboard shortcuts: in the Events screen, Ctrl+Space N will set the range selector "From" option, and Ctrl+Space W will set the "To" option, to the current time.
  • YARP-based cluster API proxy: Seq's internal cluster network now uses YARP for high-performance HTTP request forwarding.
  • Classic theme: in "Your Theme" the earlier Seq light theme is now selectable (this was also included in the most recent 2025.1 patch).
  • Browser-native scroll bars: the UI now uses browser-native scroll bars throughout.
  • Standard up/down sort marker conventions: table headers now indicate sort direction using the conventional up/down arrow semantics.
  • Message template expansion tolerance: the expanded representation of incoming events can now slightly exceed the configured size limit to improve ingestion success rates.
  • Session lifetime changes: username/password and Active Directory login sessions are no longer extended by the majority of API actions, tightening up idle session timeouts.
  • Removed "reorder input by timestamp" from app instance settings (see "Breaking changes" below).
  • Fixed rendering of events with whitespace-only messages.
  • Fixed a refresh loop triggered by scrolling down after switching off the Events "tail" feature.
  • Fixed incorrect syntax highlighting of searches determined to be free text.
  • Fixed disabling of signal indexes via the Indexing page.

Breaking changes

Seq 2025.2 is highly-compatible with Seq 2025.1 and previous versions. Two breaking changes with limited impact are included.

Initialization requirements for new instances

To reduce the chances of accidental misconfiguration, Seq 2025.2 requires an administrator password to be set, or an explicit opt-out from this, in all deployment models. Existing installs are unaffected by this change.

If you're deploying Seq via Docker you'll need to include SEQ_PASSWORD on the docker run command-line:

mkdir ./data
docker run \
  --name seq \
  -d \
  --restart unless-stopped \
  -e ACCEPT_EULA=Y \
  -e SEQ_PASSWORD=Y0urPa$$word \
  -v `pwd`/data:/data \
  -p 5341:80 \
  datalust/seq

On Windows, the default install experience handles this for you. Automated installations need a default password specified, using the seq config set command, before configuring the Seq service:

seq config set -k firstRun.adminPassword -v Y0urPa$$word
seq service install
seq service start

Both deployment models continue to support the SEQ_FIRSTRUN_ADMINPASSWORDHASH/firstRun.adminPasswordHash alternative for greater password security, and both also support SEQ_FIRSTRUN_NOAUTHENTICATION=True or seq config set -k firstRun.noAuthentication -v true to opt out of the administrator password requirement (not recommended).

Removal of disk-backed app input buffering

Seq previously supported running plug-in output apps in one of two modes:

  1. Using arrival-order in-memory buffering, or
  2. Using timestamp-order on-disk buffering

The first mode is the default, while the second was opt-in via "Reorder input by timestamp" on the app instance configuration page.

Mode 2, timestamp-order buffering on disk, was designed in an era of much lower data volumes. It's been deprecated via in-app warnings for some time, and as of 2025.2 we've removed it from the UI and HTTP API.

Upgrading

On Windows, install the MSI published at datalust.co/download. Under Docker, pull the datalust/seq:latest container image and restart to use the new version.

If you need help or have questions about Seq 2025.2, please reach out to support@datalust.co.