IronPdfEngine Docker: "Invalid IronPdfEngine version" Warning or Changed Output After Upgrading (Default Tags)

Overview

The IronPdfEngine image version moves with every release and :latest follows it, but when the client and engine versions differ, the client only logs a warning and keeps working, so output can change without an error. In 2026.11.1 the default tags :<version> and :latest still use Chromium 109, so changed output on a default tag comes from a version mismatch or from PDF-side changes, not from a new browser engine. Pin the engine tag to your client version and re-baseline the expected PDF/A-1 and PDF/UA-2 files.

[Warning] Invalid IronPdfEngine version (Server: 2026.11.1) (This client: 2026.10.3)

Environment

OS: Linux containers (linux/amd64, linux/arm64)
Hosting: Docker, Docker Compose, Kubernetes, .NET Aspire, cloud container services
Language/Runtime: .NET (IronPdf.Slim or engine mode), Java, Python, Node.js in Docker mode

Version Metadata

Version found: 2026.11.1
Version resolved: N/A

Cause

The client logs the warning above whenever the engine reports a different version, whichever side is newer; this often happens with :latest, when a restart or a new node pulls a newer engine than the application's client. Separately, 2026.11.1 changes some PDF output on every engine: PDF/A-1 output replaces embedded sRGB ICC v4 colour profiles with the equivalent v2 profile (only sRGB v4 profiles are affected), and PDF/UA-2 output writes the pdfuaid:rev value 2024 instead of 2020. Colours and validation results don't change, but byte-for-byte comparisons against older files fail.

Solution

Recommended: Pin the engine image to the same version as your IronPDF client.Docker:
```
docker pull ironsoftwareofficial/ironpdfengine:<version> 
```
Docker Compose:
```
services: 
  ironpdfengine: 
    image: ironsoftwareofficial/ironpdfengine:<version> 
    ports: 
      - "127.0.0.1:33350:33350" 
```
To be fully reproducible, you can also pin the image digest (ironsoftwareofficial/ironpdfengine@sha256:<digest>).
From now on, upgrade the client package and the engine tag together.
Confirm which engine the image contains:
```
docker inspect -f ' ' ironsoftwareofficial/ironpdfengine:<tag> 
docker logs <container> 2>&1 | head -1 
```
default means Chromium 109 and updatedchrome means Chromium 146. On a default tag, the first log line is:
```
IronPdfEngine Chromium engine: default (Chromium 109.0.5414.120, CEF 109.1.18+gf1c41e4) 
```
Images older than 2026.11.1 have no labels and are all Chromium 109.
If your tests compare PDF/A-1 or PDF/UA-2 files byte for byte, regenerate the expected files with 2026.11.1, and use a PDF/A or PDF/UA validator to confirm compliance instead. The same change applies to the in-process default IronPdf package.
If you want Chromium 146, choose it on purpose with :<version>-updatedchrome and test your documents first, because output on that engine differs from Chromium 109.

References

IronPdfEngine Docker image on Docker Hub: https://hub.docker.com/r/ironsoftwareofficial/ironpdfengine
Using IronPdfEngine with Docker: https://ironpdf.com/get-started/ironpdfengine-docker/
About IronPdfEngine: https://ironpdf.com/get-started/ironpdfengine/
Related: output PDF from IronPdfEngine Docker not as expected: https://ironpdf.com/troubleshooting/ironpdfengine-docker-output-not-as-expected/