TYPO3 errors - tips on how to fix them

In the frontend only a blank page appears or in the backend a part of the screen simply remains blank: this is usually due to a PHP error.

As the output of error messages is suppressed in most configurations, you should first switch on the display of error messages. To do this, set the parameter displayErrors in the install tool under 'All Configuration' to '-1' (in older TYPO3 versions '2'). In addition, your own IP address must be entered in the devIPmask parameter so that the errors are displayed (if the displayErrors parameter is set to '1', the errors are displayed regardless of the IP address).

Instead of in the installation tool, the parameters can also be edited or inserted directly in the file localconf.php (for TYPO3 <= 4.7) or LocalConfiguration.php (for TYPO3 >= 6.0):

$TYPO3_CONF_VARS['SYS']['displayErrors'] = '-1'; 
$TYPO3_CONF_VARS['SYS']['devIPmask'] = 'Your IP address';

In most cases, the error message provides information about the extension or area of TYPO3 in which the error occurs. It can be very helpful to enter the error message in Google...

One of the most common error messages looks something like this:

Warning: mysql_fetch_assoc(): supplied argument is not a valid 
MySQL result resource in ...\t3lib\class.t3lib_db.php on line ...

Regardless of the error, the same program line is always output as the source of the error. This is because in TYPO3 all database accesses are executed via an intermediate function (abstraction layer) - and this is where the error message comes from.

To find out which database query has failed, activate the SQLdebug function via the install tool. A detailed error message including the triggering SQL command is then displayed.

You want to try out a new extension, but after installation the website no longer works. The attempt to log in to the backend to uninstall the extension no longer works either.

This problem often occurs if the extension is dependent on other extensions that are not installed (Fatal Error: Extension ... was not loaded). Or the extension is not compatible with the TYPO3 or PHP version used.

The only solution here is to manually uninstall the extension.

As of TYPO3 CMS 8.7

Since TYPO3 6.2 the extensions are managed in the file typo3conf/PackageStates.php. Search for the extension key in this file and delete the 3 lines of the extension. Then delete the extension from the /ext directory and empty the typo3temp/ directory.

As of TYPO3 CMS 6.2

As of TYPO3 6.2, the extensions are managed in the typo3conf/PackageStates.php file. Search here for the extension key and change the status to inactive. Then empty the typo3temp/Cache/ directory.

From TYPO3 CMS 6.0

The typo3conf/LocalConfiguration.php file must be edited here. Look for the area 'extListArray' => array(...) and remove the line with the name of the extension within this array and save the file. You can then empty the typo3temp/Cache/ directory.

Up to TYPO3 CMS 4.7.x

To do this, edit the typo3conf/localconf.php file via FTP or SSH access. Look for the entry $TYPO3_CONF_VARS['EXT']['extList'] and remove the entry with the name of the extension at the end of the list. After saving, delete the files temp_CACHED... in the same directory. The website and the login should then work again.

When calling the Extension Manager, the following error message appears (here only an excerpt)

Fatal error: Uncaught exception 'ReflectionException' with message 
'Property TYPO3\CMS\Extensionmanager\Service\ExtensionManagementService::$listUtility does not exist' in... 

The problem can be solved by deleting the system cache, for this you have to change the line in the user settings of the respective user in TSConfig

options.clearCache.system = 1 

in the user settings of the respective user in TSConfig, then the system cache is still available under the cache flash.

Errors can also easily creep into TypoScript: one parenthesis too many or too few or a transposed letter and the page no longer works or a function that was actually configured is suddenly no longer available.

It makes sense to use the TypoScript Object Browser here, as error messages then appear. The line number of the error is displayed with the individual messages. The TypoScript Analyzer can be used to quickly find the location of the error by clicking on the individual modules.

Problem: In the option to link images or media, the checkbox cannot be set and the link entered disappears after saving.

Solution: The following line must be added to the localconf.php file (the setting can also be made with the install tool under 'All Configuration'):

$TYPO3_CONF_VARS['SYS']['doNotCheckReferer'] = '1';

Problem: When linking a file in the RTE, the tag <media ...> appears around the linked word after saving. The problem only occurs when using the DAM extension.

Solution: When loading the extensions, the sequence is important. Make sure that the extension rtehtmlarea is loaded before the extension DAM in the [extList] entry in the localconf.php file.

If the Rich Text Editor (extension rtehtmlarea) is not loaded, it often helps to execute the function "Reset configuration and delete temporary data" in the menu under Users ' Tools.

If images with umlauts in the file name are not displayed in the backend, you must make the following adjustment in the install tool:

$TYPO3_CONF_VARS['SYS']['systemLocale'] = 'de_DE.utf-8';

If it is only possible to call the backend in TYPO3 7 by specifying the index.php (i.e.: domain.de/typo3/index.php), it helps to add the following line to the .htaccess file in the project directory:

RewriteCond %{REQUEST_FILENAME} !-d

If the following error message appears under Admin tools in the Log menu item:

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 22471174 bytes) in /server_pfad_des_kunden/typo3/template.php

or the error 500, then the number (limit) of values to be displayed and the time have been set to infinite (no limit) under log and the entries in the sys_log are too many.
There are two solutions to solve this problem:

• Under User Tools, click the "Clear Temporary Data" button.
• Under Admin tools ' Users ' create a new backend user and delete the old user.

This message appears if you have installed the adodb and dbal extensions but have not configured them. The extension dbal is - except for rare special cases - not required on our hosting packages, as we work with MySQL databases. The dbal extension is primarily used for other database systems (e.g. Oracle).

Solution: Access to the backend is not possible, therefore the entry dbal and adodb must be manually removed from the "extList" parameter in the typo3conf/localconf.php file. Subsequently, the files temp_CACHED... in the typo3conf directory must be deleted.

Error message:

Calculated absolute path to tslib directory does not exist. 

Something in the main file, folder and link structure is wrong and must be fixed! A typical document root contains a couple of symbolic links: 
* A symlink "typo3_src" pointing to the TYPO3 CMS core. 
* A symlink "typo" - the backend entry point - pointing to "typo3_src/typo3" 
* A symlink "index.php" - the frontend entry point - points to "typo3_src/index.php"

This error message can appear, for example, when trying to upgrade to a more recent TYPO3 version.

Solution: In the domain administration of the customer menu, change the PHP edition used for the affected domain to "EXTENDED". This deactivates the PHP OPCode cache active in the "FASTCGI" setting. Once the work on the website has been completed, you can switch back to "FASTCGI", as the performance of the website is significantly better here.

Error message:

TYPO3 version > 8.7.16 the Extension Manager is no longer loaded and the following error message (excerpt) is displayed in the backend:

Warning: Uncaught TYPO3\PharStreamWrapper\Exception: 
Executing phar:///your_serverpath/your_project_directory/typo3conf/ext/typo3_console/Resources/Private/ExtensionArtifacts/../../../Libraries/symfony-process.phar/vendor/autoload.php is denied ... etc.
Fatal error: 
TYPO3\CMS\Core\Cache\Backend\SimpleFileBackend::{closure}(): 
Failed opening required 'phar:///your_serverpath/your_project_directory/typo3conf/ext/typo3_console/Resources/Private/ExtensionArtifacts/../../../Libraries/symfony-process.phar/vendor/autoload.php' (include_path='.:/usr/local/lib/php') 

Executing *.phar files is not possible for security reasons and the above error message appears, which may vary depending on the extension.

Solution: In this case, the extension "typo3_console" must be updated. To do this, add the lines in PackageStates.php

'typo3_console' => [
            'packagePath' => 'typo3conf/ext/typo3console/',
],

remove, save, empty the cache and update via the Extension Manager.

In 98% of all cases where the initial response is "I haven't changed anything", it later turns out that modifications have indeed been made. By the way, TYPO3 logs this in great detail in the system logbook...