I got this error from trying to export the Ecommerce Log and I got a similar error trying to export the Visitor Log. Saving other items like the Dashboard seems to work fine.
I’m running Piwik 1.5.1 with the patch to the Visit.php file that fixed Ecommerce events being split into 2 sessions. The error message I received was:
Notice: Array to string conversion in /var/www/html/webstats/core/DataTable/Renderer/Csv.php on line 266
Backtrace -->
#0 Piwik_ErrorHandler(…) called at [:]#1 strpos(…) called at [/var/www/html/webstats/core/DataTable/Renderer/Csv.php:266]#2 Piwik_DataTable_Renderer_Csv->formatValue(…) called at [/var/www/html/webstats/core/DataTable/Renderer/Csv.php:245]#3 Piwik_DataTable_Renderer_Csv->renderDataTable(…) called at [/var/www/html/webstats/core/DataTable/Renderer/Csv.php:132]#4 Piwik_DataTable_Renderer_Csv->renderTable(…) called at [/var/www/html/webstats/core/DataTable/Renderer/Csv.php:66]#5 Piwik_DataTable_Renderer_Csv->render(…) called at [/var/www/html/webstats/core/API/ResponseBuilder.php:200]#6 Piwik_API_ResponseBuilder->getRenderedDataTable(…) called at [/var/www/html/webstats/core/API/ResponseBuilder.php:271]#7 Piwik_API_ResponseBuilder->handleDataTable(…) called at [/var/www/html/webstats/core/API/ResponseBuilder.php:69]#8 Piwik_API_ResponseBuilder->getResponse(…) called at [/var/www/html/webstats/core/API/Request.php:123]#9 Piwik_API_Request->process(…) called at [/var/www/html/webstats/plugins/API/Controller.php:27]#10 Piwik_API_Controller->index(…) called at [:]#11 call_user_func_array(…) called at [/var/www/html/webstats/core/FrontController.php:136]#12 Piwik_FrontController->dispatch(…) called at [/var/www/html/webstats/index.php:53]
Notice: Array to string conversion in /var/www/html/webstats/core/DataTable/Renderer/Csv.php on line 267
Backtrace -->
#0 Piwik_ErrorHandler(…) called at [:]#1 strpos(…) called at [/var/www/html/webstats/core/DataTable/Renderer/Csv.php:267]#2 Piwik_DataTable_Renderer_Csv->formatValue(…) called at [/var/www/html/webstats/core/DataTable/Renderer/Csv.php:245]#3 Piwik_DataTable_Renderer_Csv->renderDataTable(…) called at [/var/www/html/webstats/core/DataTable/Renderer/Csv.php:132]#4 Piwik_DataTable_Renderer_Csv->renderTable(…) called at [/var/www/html/webstats/core/DataTable/Renderer/Csv.php:66]#5 Piwik_DataTable_Renderer_Csv->render(…) called at [/var/www/html/webstats/core/API/ResponseBuilder.php:200]#6 Piwik_API_ResponseBuilder->getRenderedDataTable(…) called at [/var/www/html/webstats/core/API/ResponseBuilder.php:271]#7 Piwik_API_ResponseBuilder->handleDataTable(…) called at [/var/www/html/webstats/core/API/ResponseBuilder.php:69]#8 Piwik_API_ResponseBuilder->getResponse(…) called at [/var/www/html/webstats/core/API/Request.php:123]#9 Piwik_API_Request->process(…) called at [/var/www/html/webstats/plugins/API/Controller.php:27]#10 Piwik_API_Controller->index(…) called at [:]#11 call_user_func_array(…) called at [/var/www/html/webstats/core/FrontController.php:136]#12 Piwik_FrontController->dispatch(…) called at [/var/www/html/webstats/index.php:53]
Those errors seem to repeat themselves many times, perhaps for each instance in my ecommerce log. I can post it all if you want me to.