PHP failed to return animated gif directly as image -

i have script generate animated gif. once work fine of sudden after file transfer , git push/pull, script not functioning!

the problem weird.

the following line used return generated gif.

header('content-type:image/gif'); echo $this->image;

standard flow image not displayed correctly, code 200 when check header in chrome developer tool.

i once thought there problem code, when double check returning normal html this:

echo '<img src="data:image/*;base64,'.base64_encode($this->image).'" />';

the image shows correctly.

any idea what's possible reason behind?

Script