Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 5 bytes)…in mysqli.php on line 483-Collection of common programming errors

I am trying to upgrade my website joomla from 1.5 to 2.5 using jUpgrade. but I am encountering this problem since a long time. jUpgrade component starts upgrading, downloads and exctracts the new joomla but while migrating the categories OR contents, it stucks and gives this error:

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Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 5 bytes) in /home/daneshna/public_html/up/libraries/joomla/database/database/mysqli.php on line 483

I tried allocating more memory size in php.ini file in the server to even 1028M (128M was the default), but this problem persists and I cant get through with it. Tried everything I could find online, but its still there.

Can anyone please help me out with this issue?

(p.s. my website is www.daneshnamah.com, a persian educational website run from Afghanistan since almost 4 years perfectly with over 6000 articles in it and over 19M visitors so far, bcz of security reasons now I wanna upgrade it to 2.5)

Thank You