Question

I have a problem with my WP site. Whenever I am trying to install W3 Total Cache plugin a white screen appears on the admin part! I've tried to install/uninstall the plugin numerous times using my FTP program but every time it is the same - white screen! Please help!

Answer 1

Try to deactivate some other wordpress plugins to see where is the conflict! When you find which one is causing the problem you can ether deactivate it or find another one with the similar functions!

Comments

I've tried this! No effect at all! :-(

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Some people say it might be a Contact us form 7 wp plugin conflict.... Do you have it?

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no, I don't...

Answer 2

I used to have the same issue! I was digging all day to find a solution, and at the end (of course) it was very simple!

My w3 total cache troubles were caused by another cashing plugin I installed before! It was this one:
Performance Optimizer Plugin for Wordpress or also called IBinc Performance Optimizer Plugin... I bought it from here - https://codecanyon.net

After a while, I've decided to add CDN to my blog and I choose to use W3 Total Cache. So I uninstalled IBinc Performance Optimizer Plugin, BUT!!!! One folder left which caused all the trouble! It is in wp-content folder and it called "cache". IBinc was storing all the information about the caching of the pages and the feeds there in files with .dat format! After the De-installation the folder left (the developers should be aware of this issue!) - and the data inside was causing the conflict with w3 total cache!

So I deleted this folder, installed W3 Total Cache (AGAIN!) and.... O! Miracle - it was working!

Conclusion: Be very careful what type of WP plugins are you installing - AND be cautions when you are removing them - trace some footprints they might have left and remove them ASAP!

Hope that helps!

Answer 3

Go with your FTP program to your public_html folder and download the error_log file. Open it with NotePad ++ and see the what is causing the problem! For me it was one plugin, so I uninstalled it

Comments

It says: [22-Apr-2013 10:32:23] PHP Warning:  array_key_exists() [<a href='function.array-key-exists'>function.array-key-exists</a>]: The second argument should be either an array or an object in /home/my site/public_html/wp-content/plugins/contact-us-form/contact-us-form.php on line 586

Answer 4

Removing the white screen can be very time consuming process! I mean finding the couse of it! I've been playing around a lot! So here what I did:

1. Delete plugin folder via ftp software (I use Filezilla) and all the other files like:
wp-content/advanced-cache.php
wp-content/db.php
wp-content/w3tc/
wp-content/w3-total-cache-config.php
wp-content/plugins/w3-total-cache/

2. Delete WT3 additions in the wp-config.php - I deleted
define('COOKIE_DOMAIN', 'mysite.com'); // Added by W3 Total Cache

3. Find every .htaccess file in your site (I found two), from the wp folder to the site root, and remove the WT3 additions. I deleted this line:
 

# BEGIN W3TC Browser Cache
<IfModule mod_deflate.c>
    <IfModule mod_headers.c>
        Header append Vary User-Agent env=!dont-vary
    </IfModule>
        AddOutputFilterByType DEFLATE text/css text/x-component application/x-javascript application/javascript text/javascript text/x-js text/html text/richtext image/svg+xml text/plain text/xsd text/xsl text/xml image/x-icon application/json
    <IfModule mod_mime.c>
        # DEFLATE by extension
        AddOutputFilter DEFLATE js css htm html xml
    </IfModule>
</IfModule>
# END W3TC Browser Cache

4. Install the plugin again. Upload and refresh.

Overall W3TC leaves a huge mess after uninstall! Even it's creator - Frederick Townes says so. So please do these 4 steps above and hopefully all will be fine. Try to install the plugin again - if no luck - use another one!

Answer 5

If you are getting this error: /wp-admin/plugins.php?activate=true&plugin_status=all&paged=1&s= at the end of the admin page. Than you may want to add this line in the wp.config file:
 

define('WP_MEMORY_LIMIT', '64M');

It will increase WP's memory size

Answer 6

Check your .httaccess file - if there are any blank rows - delete them. Helped for me...

Answer 7

Here is another solution: https://wordpress.org/support/topic/wp-admin-not-found-error/

Answer 8

You must also know!

W3 Total Cache has a conflict with:
1. Use Google Libraries (do not use it with W3 Total Cache CDN function)
2. With some premium plugins - such as https://www.tipsandtricks-hq.com/ - WP eStore
3. With this one as well - https://tribulant.com/plugins/view/1/wordpress-newsletter-plugin

The main reason the page is white is probably and in most cases conflict(s) with particular plugin(s)....