Error creating PFD invoice

When I try to create a PDF invoice, or when the customer tries to do it, there is an error:

Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 77 bytes) in /home/mysite/public_html/lib/html2pdf/value.generic.length.php on line 59


The server is out of memory, I suggest that you contact your webhost