Blank page, fatal errors after Hika 2.2.1 update.

-- url of the page with the problem -- : soundsquitereasonable.com/ 'Search Our Stock' from 'Main Menu'. Site presently hidden by password protected splash page. Will PM access if required.
-- HikaShop version -- : 2.2.1
-- Joomla version -- : 2.5.14
-- PHP version -- : 5.3.26
-- Browser(s) name and version -- : Firefox 23.0.1
-- Error-message(debug-mod must be tuned on) -- :
Fatal error: Allowed memory size of 25165824 bytes exhausted (tried to allocate 122880 bytes) in . . .
. . . /administrator/components/com_hikashop/classes/field.php on line 2118

I recently updated a site to Hika 2.2.1, but the update has brought about fatal errors, causing the site to disappear behind blank pages when HikaShop is called. These problems happen every time I run the update when HikaShop has a new release.

I have made edits to several views for layout purposes and to display custom fields (address_template, category_listing_image_title, checkout_cart, checkout_listing_price, product_cart, product_listing_image_title, product_listing_price, product_show, product_show_default), and two of these, 'product_listing_image_title' and 'product_listing_price', showed up when I activated Joomla debug.

I copied my edited version of each and installed the update default file, but the error sites just changed to other view files, and files from elsewhere in the Hika structure. The latest error messages are detailed below - please advise where I can find the view files shown (I don't recognise the '/tmpl/' in the filepaths) and how the files listed elsewhere than the 'views' folder came to cause errors, since I haven't edited any of them.

This was the first error message from the Categories Listing link -
Fatal error: Allowed memory size of 25165824 bytes exhausted (tried to allocate 122880 bytes) in . . .
. . . /administrator/components/com_hikashop/classes/field.php on line 2118

Errors also showed up from each the Product Category listing links, so I replaced the view files listed above by the default views. Now I get the errors detailed below from (a) php 'display errors' and (b) when Joomla debug is also running:

Fatal error: Allowed memory size of 25165824 bytes exhausted (tried to allocate 122880 bytes) in . . .

Category listing (Search Our Site)
(a) . . . /public_html/templates/siteground-j16-40/html/com_hikashop/product/cart.php on line 327
(b) . . . /public_html/administrator/components/com_hikashop/classes/field.php on line 2118

(Product listing) 45Singles
(a) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_div.php on line 79
(b) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_img_title.php on line 99

(Product listing) 45 EPs
(a) . . . /public_html/components/com_hikashop/views/product/tmpl/quantity.php on line 66
(b) . . . /public_html/components/com_hikashop/views/product/tmpl/quantity.php on line 66

(Product listing) 12" Singles
(a) . . . /public_html/components/com_hikashop/views/product/tmpl/quantity.php on line 66
(b) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_div.php on line 79

(Product listing) 33 Albums
(a) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_div.php on line 79
(b) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_img_title.php on line 99

(Product listing) CD Albums
(a) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_img_title.php on line 99
(b) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_price.php on line 73

(Product listing) CD Singles
(a) . . . /public_html/components/com_hikashop/views/product/tmpl/quantity.php on line 66
(b) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_div.php on line 79

(Product listing) 78 Records
(a) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_img_title.php on line 99
(b) . . . /public_html/components/com_hikashop/views/product/tmpl/quantity.php on line 66

(Product listing) Memorabilia
(a) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_price.php on line 73
(b) . . . /public_html/components/com_hikashop/views/product/tmpl/listing_img_title.php on line 99

Assuming I can get the site correctly functioning again, what can I do to prevent these problems happening at the next update?

Thankyou.

PS. FYI: Under 'How to know if it comes from that (for update issues)?' in the HikaShop FAQ, the option "Use AJAX when possible for add to cart buttons" is not under the 'Checkout' tab of the HikaShop 'Configuration', but in 'Advanced settings' under the 'Main' tab of the same section.

Thanks Jerome, sorted!!

For the sake of any others who may encounter the same problem, the memory limit referred to above is not the web space allocated to your site, but the limit expressed in your site's php.ini file. PHP has a built-in limit on the amount of memory it will allocate. If that limit is reached, the process will exit with an error message similar to this:
"Fatal error: Allowed memory size of 25165824 bytes exhausted (tried to allocate 122880 bytes) in . . ."

This is usually the result of the PHP script trying to load a large file, or files, into memory all at once, but it is possible to increase the memory limit to avoid this problem. To do this, open the php.ini file in your site's root folder and add, or edit, the following line: memory_limit=32M

The default is 32M (32 megabytes), so you should replace the '32' with whatever value is appropriate (eg. '64'). If you are using PHP 5.0+, you may also need to check for user.ini files in the same directory which may be overriding your settings (eg. 'php5.ini').

If this does not resolve the problem, you can also increase the web server memory limit by editing, or creating if it does not exist, the ".htaccess" file in the same root folder, and adding the following line: RLimitMem max

Both php.ini and .htaccess files should be created in plain text (eg. Notepad on Windows or TextEdit in Plain Text mode on Mac) to avoid any formatting information being saved. Editors such as WordPad, MS Word, and TextEdit in its default Rich Text mode will produce unreadable files.

Cheers all.