Stefan Helander

WordPress shows white page after site move

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WordPress just showing a white page means it is experienceing PHP errors. When it occurs after a site has been moved from one hosting to another it can be caused by several reasons.

To make it possible to track down the cause you can temporarily add the following to the .htaccess file in the root. If this gives you a internal server error 500 it means it is not allowed by the host. If allowed, you will get error messages from PHP dispayed on screen when accessing the site:

php_flag display_startup_errors on
php_flag display_errors on

There are visbible PHP ending tags ?> on the site

If you see more or less normal output from the site but once in a while you see lines ending with ?>. This can happen if the site has been running on PHP 5 where the short PHP start tag <? is allowed (instead of the longer <?php.

If the site has been moved to PHP 7 where this is not longer allowed, it can cause this kind of strange behaviour.

If you don’t want to go through all the code and find all the occurrences of <? and replace them with <?php (which is one solution), you can simply add the following to your php.ini:

short_open_tag=On

You need to restart Apache after this.

Wordfence plugin is installed

You need to manually edit the system specific paths in the following files:

  • .user.ini in the site root, change the path after auto_prepend_file
  • wordfence-waf.php in the site root, change the paths on all occurrences

WP Rocket plugin is installed

The file wp-content/advanced-cache.php contains system specific paths. You can manually update them or just simply delete the file and login to wp-admin of the site and it will be recreated automatically with the correct paths.

Stefan Helander

MySQL Error 1215: Cannot add foreign key constraint

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Check that both tables have the same engine type, so there isn’t a mix of for example MyISAM and InnoDB.

Stefan Helander

rm unable to delete file even as root or sudo [Solved]

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When it is not possible to delete a file using rm even when logged in as root or by using sudo, check the file attributes with:

lsattr filename.ext

If it has the “i” attribute, this is preventing the file from being deleted, even by super users. When you have verified the reason for this and still want to delete the file then remove the “i” attribute with:

chattr -i filename.ext

Then delete the file using rm as you normally would.

Stefan Helander

Ispconfig3: Let’s Encrypt not working

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There can be several reasons for Let’s Encrypt certificates not being issued for sites. These are some things to check:

  • When creating a new website, save it first, then open it again and check Let’s encrypt and then save it (i.e. don’t check the Let’s Encrypt unless the website has been saved at least once in Ispconfig3)
  • Delete any existing certificates under the SSL tab for the website, including self signed
  • Check that all host names for the website and webaliases are pointing to the correct server
  • Use A records, not CNAME
  • Make sure there are no redirects on the website
  • Check for error messages in the log file; /var/log/letsencrypt/letsencrypt.log
  • If you get messages in the letsencrypt.log file like;
    “Please choose an account
    Choises: “
    Then check /etc/letsencrypt/accounts/acme-v01.api.letsencrypt.org/directory and if there are more than one account (subdirectory) move all but one to another location.
  • Check the web logs for the site, both access and error logs, for accesses to .well-known/acme-challenge/* and verify that they are served properly (status code 200)
Stefan Helander

Roundcube – add client’s IP-address and host name to outgoing email headers

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By default, the logged in client’s IP-address and hostname are not present in the outgoing email headers which makes it hard to trace the origin in case of abuse.

To make roundcube add this to the email headers of outgoing email, put this in the roundcube configuration file:

// put user's ip and host name in mail headers to enable trace
$config['http_received_header'] = true;

Stefan Helander

Ispconfig3: awstats/webalizer not working, client web logs empty

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If awstats or webalizer is not containing any data and the client web logs are empty, the cause might be missing mounts of the log directories in /etc/fstab.

Search /etc/fstab for the client domain name. If no log mount is found, add a line for the client web site manually in this form:

/var/log/ispconfig/httpd/DOMAIN.COM /var/www/clients/clientNNN/webNNN/log    none    bind,nobootwait    0 0

After that do:

mount -a
mount

to verify it is mounted. After nightly cron, check that awstats or webalizer contains data.

Stefan Helander

Asterisk / FreePBX sip trunk registration problem, Serious Network Trouble

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The asterisk log file (/var/log/asterisk/full) shows entries like this:

[Sep  3 04:02:08] ERROR[3984] chan_sip.c: Serious Network Trouble; __sip_xmit returns error for pkt data

Solution: The server had been moved from one public IP-address to another. In Asterisk PBX settings, the fields for both External IP and Bind Address (under Advanced) needed adjustment to the new IP-address. After server reload everything worked normally.

Stefan Helander

/etc/cron.daily/amavisd-new: Please run this cronjob as user amavis

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After a system update I started to receive cron messages saying “/etc/cron.daily/amavisd-new:
Please run this cronjob as user amavis”.

It turns out that this happens because the cron script is replaced by a new one located in /etc/cron.d and the one in /etc/cron.daily is left behind giving this error message.

Solution: After checking that the new script exists in /etc/cron.d, just delete /etc/cron.daily/amavisd-new

More information about this here (bug report).

Erik Svensson

MySQL 5.7 and mysql_secure_installation

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If you are using mysql:secure_installation witch you should, beware of that the script reset all passwords in the SQL server database mysql. To fix this problem use the following.
Root password:
ALTER USER ‘root’@’localhost’ IDENTIFIED BY ‘MyNewPass’;
Session password:
ALTER USER ‘mysql.session’@’localhost’ IDENTIFIED BY ‘password’ PASSWORD EXPIRE NEVER;

Exampel error messages:
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

Netbeans and git over ssh
Stefan Helander

Netbeans 8.2, git clone over ssh “Incorrect credentials for repository at ssh://”

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Trying to git clone a repository over ssh in Netbeans 8.2 displaying an error message saying “Incorrect credentials for repository at ssh://” gave me a bit of a headache. I could successfully connect to the repository server using ssh from the terminal in my Mac running OSX.

Netbeans and git over ssh

After spending some time troubleshooting I tried to check for updates in Netbeans and that gave me an error message saying Netbeans could connect to the Internet in order to check for updates.

It turned out the problem was not incorrect credentials for SSH when trying to git clone, but in reality Netbeans could just not access the Internet. This was caused by the TripMode application I am using to control which applications can access the Internet when I am on mobile broadband where data rates applies.

So the error message “Incorrect credentials for repository at ssh://” in Netbeans can be misleading. It can be caused by the fact Netbeans just can’t connect at all to the repository server.