glBlitFramebuffer Invalid Operation

I've been messing around with framebuffers and render to texture and I came across the need to blit them. Again on some machines I get a GL_INVALID_OPERATION right after the glBlitFramebuffer call. Each texture bound to the framebuffer is setup the exact same way, all the same size and parameters. Also, when I try to blit one entire texture (previously succesfully rendered to) to another framebuffer, only the destination 'rectangle' to write in is smaller than the rectangle to read from (e.g. when I want to blit it to a quarter of the screen), it throws a GL_INVALID_OPERATION too.

EDIT: Actually it always throws the error whenever the rectangles to read from and draw to have a different size, so I can't blit to a texture of a different size, or the same size but a different sized 'render to' area...?

Everytime I blit to a manually generated framebuffer the status is checked through glCheckFramebufferStatus and it always returns GL_FRAMEBUFFER_COMPLETE.

-BIGGEST SNIP EVER-, see below for shorter 'source code', obviously a couple C++ errors and not complete, but its only for the GL calls

The OpenGL error occurs when I call the last method of the viewport (Viewport::blit) with the screen framebuffer as target (by passing NULL). It first sets the read buffer of its own framebuffer (the draw buffers were already set) and then it calls RenderTarget::blit which calls glBlitFramebuffer. In the blit method it binds both buffers, and you can see it calls glCheckFramebufferStatus there which does not return an error.

I've been reading this over and over but I can't seem to find the error that causes it. When I blit the color buffer I use GL_LINEAR, otherwise I use GL_NEAREST All color buffers use GL_RGB32F as internal format and the depth buffer (which I never blit) uses GL_DEPTH_COMPONENT32F

EDIT, a shorter example, just took all the GL calls and filled the params I used

glBindFramebuffer(GL_READ_FRAMEBUFFER, _GL_Framebuffer);
glReadBuffer(GL_COLOR_ATTACHMENT0 + index);
glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);

// OpenGL error check, does not return an error

glBindFramebuffer(GL_READ_FRAMEBUFFER, _GL_Framebuffer);
GLenum status = glCheckFramebufferStatus(GL_READ_FRAMEBUFFER);
if(status != GL_FRAMEBUFFER_COMPLETE)
{
    // Some error checking, fortunately status always turns out to be complete
}
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);

glBlitFramebuffer(0, 0, screenWidth, screenHeight, 0, 0, screenWidth, screenHeight, target, (target == GL_COLOR_BUFFER_BIT) ? GL_LINEAR : GL_NEAREST);

// If the source/destination read/draw rectangles are different in size, GL_INVALID_OPERATION is cought here

And the Framebuffer/Texture creation:

glGenFramebuffer(1, &_GL_Framebuffer);

glGenTextures(1, &_GL_ZBuffer);
glBindTexture(GL_TEXTURE_2D, _GL_ZBuffer);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32F, screenWidth, screenHeight, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glBindTexture(GL_TEXTURE_2D, 0);

glBindFramebuffer(GL_FRAMEBUFFER, _GL_Framebuffer);
glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT + 0, _GL_ZBuffer, 0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

int writeIndices[BUFFER_COUNT];
for(unsigned int i = 0; i < BUFFER_COUNT; ++i)
{
    writeIndices[i] = i;

    glGenTextures(1, &_GL_Texture);
    glBindTexture(GL_TEXTURE_2D, _GL_Texture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB32F, screenWidth, screenHeight, 0, GL_RGB, GL_FLOAT, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glBindTexture(GL_TEXTURE_2D, 0);

    glBindFramebuffer(GL_FRAMEBUFFER, _GL_Framebuffer);
    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + i, _GL_Texture, 0);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

    // In the actual code each texture is obviously saved in an object
}

GLenum *enums = new GLenum[BUFFER_COUNT];
for(unsigned int i = 0; i < BUFFER_COUNT; ++i)
{
    // Get index and validate
    int index = *(indices + i); // indices = writeIndices
    if(index < 0 || index >= maxAttachments)
    {
        delete[] enums;
        return false;
    }

    // Set index
    enums[i] = GL_COLOR_ATTACHMENT0 + index;
}

// Set indices
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, _GL_Framebuffer);
glDrawBuffers(BUFFER_COUNT, enums);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);

delete[] enums;

// OpenGL error check, no errors

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