Umbrello/FAQ
What are the different versions of Umbrello ?
The current stable version 25.12.1 is based on KDE Frameworks 6.
When submitting bug reports with Umbrello it is helpful if you have tested against a recent build from the Umbrello app page.
Can I use Umbrello command line features without a graphical environment?
Umbrello is a Qt-based GUI application and currently requires a graphical Qt platform plugin to run. Fully headless operation without any display server is not supported.
As a workaround, Umbrello can be executed using a virtual display, for example via
xvfb-run umbrello
on Unix-like systems. This provides a virtual framebuffer without visible output.
This limitation is related to Umbrello’s GUI-centric architecture rather than the underlying operating system.
Can I submit a patch ?
We love patches. Patches should be based on a recent Git clone, which can be obtained from the umbrello project page, and are submitted via a merge request for the listed project. For more information, see the documentation for KDE GitLab.
Umbrello takes up too much memory ?
Switch to a code generator other than C++ or Java. Recent Git versions also allow Undo to be switched off. Current Umbrello handles memory much better than previous versions for large diagrams.
How can I install the development version in parallel to the production version ?
To build Umbrello from source, all required build dependencies (Qt 6, KDE Frameworks 6, and development tools) must be installed. The exact package names depend on your distribution.
The recommended way to build Umbrello for development is to use kde-builder, which automatically handles dependencies and installs everything into a separate prefix without interfering with the system version.
For details, see: https://community.kde.org/Get_Involved/development/kde-builder
Alternatively, Umbrello can be built manually using CMake in a custom prefix:
git clone https://invent.kde.org/sdk/umbrello.git
mkdir build
cmake -DCMAKE_INSTALL_PREFIX=$HOME/umbrello-dev ..
cmake --build .
cmake --install .
Ensure that the chosen prefix is included in your PATH if you want to start the development version directly from the command line.
Modern KDE Frameworks versions use standard XDG paths, so manual adjustment of KDEDIRS or similar variables is no longer required.
Can I help translate Umbrello into my spoken language ?
Certainly. As part of KDE you will have to work with the KDE i18n team for your language https://i18n.kde.org.
Umbrello contains some UML and programming specific terms. Take care to research the most understandable translations of these terms for your spoken language.
How do I write a code generator ?
First check that there isn't already one in the KDE Git version of Umbrello.
Then read the instructions in codegenerator.h and use one of the other generators as a template. The C++ and Java code generators are a lot more advanced than the rest, it would be nice to have the others offer the same functionality as them.
Why the silly name ?
The program's name is Umbrello UML Modeller. The shortened form is Umbrello. When translating it translate UML Modeller in the most sensible way or if it can not be easily translated it can be left out. Umbrello should generally be left as is when translating to Latin alphabet languages.
Previously the program was called UML Modeller or UML Object Modeller or just UML. This was considered too generic by packagers and others. After some consultation and a public vote Umbrello showed surprising popularity, so the name Umbrello UML Modeller is now used. Umbrello does not mean anything as far as we know.
In sequence diagrams how do I extend the object's lifeline ?
Drag a message arrow downwards.
In previous versions you had to click and drag with the mouse at the bottom of the object's vertical line.
My package format is not supported and I can't install from source, what do I do ?
Contact us and if there are enough requests, we may be able to find a way to help you.
Can I have Git write access ?
The Umbrello sources are located at KDE GitLab. Anyone with a KDE GitLab account (see the related documentation) can request changes by opening a merge request.
Can I have bugs.kde.org write access ?
To report a bug at https://bugs.kde.org, you need to have an account there. See New Account.
Some UML features that I need don't seem to be supported ?
Let us know what features you require. The most requested features will be the first features introduced.
What file format does the program use ?
Umbrello uses an XML-based file format derived from XMI. Older versions (prior to 1.4) used a loosely XMI-inspired format that was not fully compatible with other UML tools.
Current Umbrello versions support importing a subset of XMI 1.x and limited XMI 2.x (UML 2.x) elements that map to features implemented in Umbrello. Diagram Interchange (UML-DI) is not supported.
If you encounter interoperability issues with XMI import or export, please report them via bug #56184 with a minimal test file and tool/version details.
Why don't I have any icons on the toolbar ?
Missing toolbar icons are usually caused by an incomplete or inconsistent KDE Frameworks or icon theme installation.
Ensure that:
- A valid icon theme (for example Breeze) is installed
- Qt can locate its platform plugins and icon resources
- Umbrello is started in a properly configured desktop environment
When running Umbrello from a custom installation prefix, verify that required runtime dependencies are found before starting the application.
I can't export diagrams as images, it complains about the mime type ?
This problem is usually caused by missing image format plugins or an incomplete Qt or KDE Frameworks installation.
Ensure that:
- Qt image format plugins (e.g. PNG, SVG) are installed
- Required runtime dependencies are available
- The application is started in a properly configured environment
If the problem persists, report it with details about the platform, Qt version, and image format being exported.
Does Umbrello run on Windows ?
Yes. There are currently developer versions of Umbrello here.
My problem still isn't solved - help!
If it is a user related problem, send an e-mail to the Umbrello mailing list. If it is a developer problem, try the Umbrello development mailing list. Details of the mailing lists can be found on the Umbrello Developer Resources page.
My user-mode-linux won't work ?
Try asking User Mode Linux.
How do I print a diagram on multiple pages ?
Multi page printing could be performed by using pdf output and pdfposter, which is available in many distributions for example:
Example
- print diagram to pdf using a0 page size
- to print out on a3 pages run
pdfposter -mA3 -pA4 <input-file> <outputfile>
How to fix the error message 'There was a problem saving file' ?
This error can have several causes:
- Attempting to save files to a write-protected directory
- Insufficient permissions for the target location
- Saving to remote URLs (http, https, ftp) without proper write access
- Missing or misconfigured KDE Frameworks runtime components
On Windows systems, security software or firewalls may block required helper processes. Ensure that Umbrello is allowed to access the filesystem and spawn helper processes. If the issue persists, test saving to a local directory and report the problem with platform and framework version details.
New FAQ Entries Suggested from Resolved Bugs
Why do class diagram association ends sometimes overlap or not move with the class?
Problem: In some older versions of Umbrello, dragging a class could cause association lines or ends to stay in the wrong position or overlap other diagram elements.
Solution: This behavior has been fixed. Make sure you are using Umbrello 25.08.2 or later to avoid this issue. Reference: KDE Bug #425678
What XMI formats does Umbrello support, and what should I do if import fails?
Problem: Umbrello supports a subset of XMI for import and export. Some UML tools use XMI dialects that Umbrello may not fully recognize, leading to incomplete or incorrect model imports.
Solution: Test the specific XMI file with Umbrello. If issues occur, try exporting the XMI using a different version or tool. Reporting a sample file to KDE Bugzilla helps the developers improve compatibility. Reference: KDE Bug #56184
Why doesn’t Umbrello support certain diagram exports like Graphviz?
Problem: Certain UML diagram features, such as aggregation links or specialized export formats (e.g., Graphviz DOT files), may not be fully supported in Umbrello.
Solution: Use alternative export formats supported by Umbrello, such as PNG or SVG for diagrams. For more advanced needs, consider exporting XMI to another UML tool that supports Graphviz.
How can I align elements precisely in a diagram?
Problem: Placing classes, components, or other diagram elements neatly can be difficult without visual guides.
Solution: Umbrello now includes alignment guides and snapping to help you position elements more precisely while arranging your diagrams. The guides work even when zoomed in or out.
Fixed since version: 25.11.90 Reference: KDE Bug #405409
Problem: In older versions, right-clicking on the Associations page of a class’s properties dialog did not show the expected context menu, making it hard to add or modify associations.
Solution: This issue has been fixed in recent versions. Right-clicking now correctly displays the context menu for editing associations.
Fixed since version: 25.11.90 Reference: KDE Bug #512239