https://en.wikipedia.org/w/index.php?title=Template:Timeline_History_of_Computing fails to render. It used to work. The error message is:
EasyTimeline 1.90 Timeline generation failed: 1 error found Line 14: ScaleMajor = unit:year increment:10 start:1940 gridcolor:grid1 - Scale attribute 'grid' invalid. Unknown color ''. Specify command 'Color' before this command.
Found it! grid1 and grid2 are predefined colors with the preset TimeHorizontal_AutoPlaceBars_UnitYear
2407 elsif ($Preset =~ /TimeHorizontal_AutoPlaceBars_UnitYear/i) {
...
2422 &StoreColor("canvas", &EncodeInput("gray(0.7)"), "");
2423 &StoreColor("grid1", &EncodeInput("gray(0.4)"), "");
2424 &StoreColor("grid2", &EncodeInput("gray(0.2)"), "");I guess it get confused when ones tries to redefine a color. The workaround is to use different color names such as grid_one and grid_two.
Note: EasyTimeline is deprecated so it is unlikely anyone will fix the underlying bug. My recommendation is to change the color name, verify it works and close this task :]