Known Issues

If NetLogo malfunctions, please send us a bug report. See the "Contacting Us" section for instructions.

Known bugs (all systems)

Language/engine bugs

• The array and table extensions are only partially compatible with the importing worlds feature. When you export a NetLogo world (using the export-world command or Export World menu item), arrays and tables are exported "by value". This means that if you have the same array or table stored in more than one location, then when it is exported and re-imported, there will now be a distinct arrays or tables in each of the places the original array or table appeared. These duplicates will initially contain the same values, but if one duplicate is altered, the others will not change.
• "Export World" does not save the state of any open files used by the file primitives. If you have a file open, export the world, and then import that world into NetLogo, you will need to re-open that file before resuming the run.
• A bug in Java causes patch colors imported using import-pcolors to be brighter than the original if the original image has a grayscale palette. To work around this issue, convert the image file to an RGB palette.

Other bugs

• Out-of-memory conditions are not handled gracefully
• the "Snap to Grid" feature is disabled when zoomed in or out
• Drawing and then erasing a line in the drawing may not erase every pixel exactly.
• Extensions that require additional external jars don't work from models saved as applets (we are already working on fixing this)
• The 3D View doesn't work on some graphics configurations; on others the 3D View works but 3D full screen mode doesn't
• The size of the fonts used in a model's interface can vary somewhat from computer to computer and from platform. As a result, text that fits in a given space on one computer may not fit in another. To avoid this problem, it is advisable to leave some extra space in the sizes of buttons, sliders, etc.
• When running a model headless (from the command line), if the model was created in an earlier NetLogo version, it may not work properly. Use the GUI to open and resave the model in the current NetLogo version before running it headless.

Windows-only bugs

• On some machines distance, in-radius, and related primitives sometimes return wrong answers due to a bug in Java. See the FAQ for ways to work around this problem.
• The "User Manual" item on the Help menu does not work on every machine (Windows 98 and ME are most likely to be affected, newer Windows versions less so)
• On some laptops, the Procedures and Info tabs may become garbled when you scroll them. To avoid this bug, reduce the size of the NetLogo window and/or reduce the color depth of your monitor (e.g. change from 32-bit to 16- or 8-bit color). This is a bug in Java itself, not in NetLogo per se. For technical details on the bug, see http://developer.java.sun.com/developer/bugParade/bugs/4763448.html (free registration required). NetLogo users are encouraged to visit that site and vote for Sun to fix this bug.

Macintosh-only bugs

• When opening a model from the Finder (by double-clicking on it, or dragging it onto the NetLogo icon), if NetLogo is not already running, then the model may or may not open; the bug is intermittent. (If NetLogo is already running, the model always opens.)
• On Mac OS X 10.4 only, the "Copy View" and "Copy Interface" items may not work: the resulting image is distorted. The workaround is to use the "Export View" and "Export Interface" items instead. This issue will go away if you use Software Update to get the latest Java from Apple.
• On versions of Mac OS X prior to 10.4, it is possible for NetLogo's menus to get confused so that the "Quit" item does not work. If this happens, you can quit NetLogo by pressing the red close button on the left end of the NetLogo's title bar.

Linux/UNIX-only bugs

• User Manual always opens in Mozilla, not your default browser. One possible workaround is to bookmark the file docs/index.html in your favorite browser. Another workaround is to make a symlink that's called "mozilla" (that's the command name NetLogo tries to run), but actually runs a different browser.
• We have discovered a problem on Linux where the "exp" reporter sometimes returns a slightly different answer (differing only in the last decimal place) for the same input. According to an engineer at Sun, this should only happen on Linux kernel versions 2.4.19 and earlier, but we have observed the problem on more recent kernel versions. We assume the problem is Linux-specific and does not happen on other Unix-based systems. We are not sure if the problem ever occurs in practice during actual NetLogo model runs, or only occurs in the context of our testing regimen. The bug in the Sun's Java VM, and not in NetLogo itself. We hope that only the "exp" reporter is affected, but we can't be entirely certain of this. NetLogo users are encouraged to visit http://developer.java.sun.com/developer/bugParade/bugs/5023712.html (free registration required) and vote for Sun to fix this bug.
• If NetLogo cannot find the font Lucida, menus will be illegible. This has been known to happen on Fedora Core 3, after upgrading packages. Restarting the X Font Server (xfs) has resolved the problem in all reported cases.
• Sun's 1.5.0 Java runtime has display problems with GTK 2.0 and NetLogo. Issues may include windows not updating properly, interface elements being strangely sized, menus being cut-off at the bottom, and weird characters appearing on the view. To avoid these issues, upgrade to Java 1.6.

Known issues with computer HubNet

See the HubNet Guide for a list of known issues with computer HubNet.