Dear all
I have problem when I making search for image in joomla >> k2 >> item >> image.
I receive this error:

Invalid backend response.
Data is empty.

I searched from google for solution. there are one idea for this issue its:
enable proc_open() functions in php.ini
but from disabled functions in php.ini I dont find proc_open().

Note: Kindly open attach file

Which Joomla and K2 version do you use?

joomla 2.5.6
k2 2.5.7

I believe you mean K2 2.6.7 right?

no 2.5.7

I'm using
joomla 2.5.18
k2 2.5.7

@Alan

K2 2.5.7 is not supported anymore. You need to update to K2 2.6.7. Get a backup of your site first just in case something goes wrong.