Commenting and adding attachments to an issue causes 500 error

This might be useful in debugging the problem:
79aec78856334f08be4406a9d2aff0be$dffc00d3524eed0dafc08fd3f2c06501

Tried several times to comment/add attachment (image) through edit issue, but all the times I got the 500 error page.

The attachment is succesfully uploaded, but the comment is lost