Is that a limit set for the trial version? Does a licenses version allow for more vertices?
EasyGerb can store a maximum of 16k points (X,Y) per polygon, which means that if you a have a complex polygon with many curves and high-arc resolution, chances are you may exceed the 16k limit.
Note: Depending on the Gerber photoplotter used, there is actually a limit of the maximum number of verticies that will successfully plot to film (from 10k to 32k vertices).
Fortunately there are several workarounds
1. Check the "Circular Interpolation" option before converting your files. What this does is place "true arcs" in your polygon so that many points aren't used to estimate each arc. This will give you better quality and smaller gerber files. The only downside is some Gerber Viewers, and photo plotters cannot handle arcs.
To set Circular Interpolation option:
A. Start EasyGerb...
B. Click the button "Options..."
C. Check the option "Use Circular Interpolation", and press OK.
D. Proceed with the EasyGerb conversion as normal.
2. You can decrease the Arc Deviation value. This will definitely decrease the amount of verticies in the polygons, and in most cases there will not be any visible difference in the quality of the arcs.
3. You can "slice" the large polygons into smaller polygon segments. I have included a simple AutoCAD movie tutorial showing how to split a polygon.