In my store nearest 16,000 products are there, when i try to export both ways import/export or dataflow both are error. But when i export minimum of data i can able to export my products, which means i can't able to export all my products at a single file.
system - import/export - export error :
system - import/export - dataflow profiles - export all products error :
You probably need to change the php memory limit.
In your php.ini, you'll find the following
Increase the value and see if it's run better
If you're with a share host, may be the new value won't be take into account