According to the documentation (in English):
Blank pages or some missing sections
If you transfer a large amount of code, using
WriteHTML() either as CSS styles or as HTML code, you can get a blank page as a result.
The PHP function
preg_replace() has a maximum string length that will scan, by default, around 100,000 characters. On this, if it is exceeded, PHP will silently return a null value. Therefore, long strings of code will be replaced by nothing!
You can increase the value of pcre.backtrack_limit in Run time if your system allows it.
pcre.backtrack_limit is configurable from PHP > = 5.2.0
As a solution: Divide your HTML into fragments and pass them one at a time to
The program dies without displaying an error message when generating a large PDF file
There is a timeout due to Apache settings
TimeOut will cause the script to finish without displaying an error message.
As a solution: Increase the PHP time limit.