Does not define type

[ChrisW67]

What does the top of field.cpp look like? Is it really in the root directory of you drive as this would imply?

In file included from ../mainwindow.h:6,
/field.h:13,
from \field.cpp:1:  <<<<< here

In file included from ../mainwindow.h:6,
/field.h:13,
from \field.cpp:1:  <<<<< here

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Is everything in the same directory?
Is there more than one file called "field.h" in your project?