[OJS 3.2.1.1] Generation of PKP Usage statistics report fails with 500 Http error

Hi @asmecher, these are our log for the problem. My IT staff says it it the same error and log message of this thread, but I’m not so sure that an update (as you say on that thread) can solve the problem because @marchitelli has the same 500 issue on 3.2…
Can you see if there are two (or more: actually I’m counting 3 thread: this, the above one, and this, plus one in italian) different 500 issues spread on different versions, or if the problem is only one?
@latha_ojs, can you provide your logs about PKP Usage statistics report?
Thank you very much, best regards
Stefano

PHP message: PHP Fatal error: Uncaught Error: [] operator not supported for strings in /xxxxx/xxxxx/xxxxx/classes/statistics/MetricsDAO.inc.php:34 Stack trace: #0 /xxxxx/xxxxx/xxxxx/plugins/generic/usageStats/PKPUsageStatsReportPlugin.inc.php(84): MetricsDAO->getMetrics('ojs::counter', Array, 'a:1:{s:10:"cont...', 'a:1:{s:5:"month...', NULL)\n #1 /xxxxx/xxxxx/xxxxx/plugins/generic/usageStats/OJSUsageStatsReportPlugin.inc.php(32): PKPUsageStatsReportPlugin->getMetrics('ojs::counter', Array, 'a:1:{s:10:"cont...', 'a:1:{s:5:"month...', NULL)\n #2 /xxxxx/xxxxx/xxxxx/lib/pkp/pages/management/PKPToolsHandler.inc.php(208): OJSUsageStatsReportPlugin->getMetrics('ojs::counter', Array, 'a:1:{s:10:"cont...', 'a:1:{s:5:"month...')\n #3 /xxxxx/xxxxx/xxxxx/lib/pkp/pages/management/PKPToolsHandler.inc.php(64): PKPToolsHandler->generateReport(Array, Object(Request)) referer: https://riviste.unimi.it/index.php/noema/management/tools