Error unlinking csv file while running cronjob

As requested by The piwik program itself, I’m posting a full backtrack of an error i’m having since I’m running version 1.5.1

The dir /var/www/tmp/assets/ has chmod 777


There is an error. Please report the message and full backtrace in the Piwik forums (please do a Search first as it might have been reported already!).

Warning: unlink(/var/www/tmp/assets/archive_blob_2011_01-9120419cc3a853e337fcd4e565e9a44f.csv): No such file or directory in /var/www/core/Piwik.php on line 2313

Backtrace -->
#0 Piwik_ErrorHandler(…) called at [:]#1 unlink(…) called at [/var/www/core/Piwik.php:2313]#2 Piwik::tableInsertBatch(…) called at [/var/www/core/ArchiveProcessing.php:741]#3 Piwik_ArchiveProcessing->insertBulkRecords(…) called at [/var/www/core/ArchiveProcessing.php:687]#4 Piwik_ArchiveProcessing->insertBlobRecord(…) called at [/var/www/core/ArchiveProcessing/Period.php:179]#5 Piwik_ArchiveProcessing_Period->archiveDataTable(…) called at [/var/www/plugins/Referers/Referers.php:245]#6 Piwik_Referers->archivePeriod(…) called at [:]#7 call_user_func_array(…) called at [/var/www/libs/Event/Dispatcher.php:284]#8 Event_Dispatcher->postNotification(…) called a t [/var/www/core/PluginsManager.php:609]#9 Piwik_PostEvent(…) called at [/var/www/core/ArchiveProcessing/Period.php:259]#10 Piwik_ArchiveProcessing_Period->compute(…) called at [/var/www/core/ArchiveProcessing.php:429]#11 Piwik_ArchiveProcessing->launchArchiving(…) called at [/var/www/core/Archive/Single.php:217]#12 Piwik_Archive_Single->prepareArchive(…) called at [/var/www/core/Archive/Single.php:246]#13 Piwik_Archive_Single->get(…) called at [/var/www/core/Archive/Single.php:424]#14 Piwik_Archive_Single->getNumeric(…) called at [/var/www/core/Archive/Array.php:89]#15 Piwik_Archive_Array->getNumeric(…) called at [/var/www/plugins/VisitsSummary/API.php:110]#16 Piwik_VisitsSummary_API->getNumeric(…) called at [/var/www/plugins/VisitsSummary/API.php:116]#17 Piwik_VisitsSummary_API->getVisits(…) called at [:]#18 call_user_func_array(…) called at [/var/www/core/API/Proxy.php:179]#19 Piwik_API_Proxy->call(…) called at [/var/www/core/API/Request.php:121]#20 Piwik_API_Request->process(…) called at [/var/www/plugins/API/Controller.php:27]#21 Piwik_API_Controller->index(…) called at [:]#22 call_user_func_array(…) called at [/var/www/core/FrontController.php:136]#23 Piwik_FrontController->dispatch(…) called at [/var/www/index.php:53]

Why does this error occur, and how can i fix this? I’ve been searching the forum and i can’t find any other related post. Only one, which was in german, and in that case the rights of the assest dir where probably not correct. But that’s not the case here.

Regards,
Mark