Hi @Vitaliy,
our error_log file is huge. It is cluttered with error messages like here: [OJS 3.1.2.0, PHP 7.72stable] PHP Deprecated Errors.
However, after searching a little bit, I found the following entries:
[19-Mar-2020 09:58:56 Europe/Berlin] PHP Fatal error: Uncaught Error: Call to undefined method IssueDAO::getIssueByArticleId() in /home/suburban/public_html/sys/plugins/generic/htmlArticleGalley/HtmlArticleGalleyPlugin.inc.php:177
Stack trace:
#0 /home/suburban/public_html/sys/plugins/generic/htmlArticleGalley/HtmlArticleGalleyPlugin.inc.php(81): HtmlArticleGalleyPlugin->_getHTMLContents(Object(Request), Object(ArticleGalley))
#1 /home/suburban/public_html/sys/lib/pkp/classes/plugins/HookRegistry.inc.php(107): HtmlArticleGalleyPlugin->articleViewCallback('ArticleHandler:...', Array)
#2 /home/suburban/public_html/sys/pages/article/ArticleHandler.inc.php(220): HookRegistry::call('ArticleHandler:...', Array)
#3 /home/suburban/public_html/sys/lib/pkp/classes/core/PKPRouter.inc.php(390): ArticleHandler->view(Array, Object(Request))
#4 /home/suburban/public_html/sys/lib/pkp/classes/core/PKPPageRouter.inc.php(231): PKPRouter->_authorizeInitializeAndCallRequest(Array, Object(Request), Array, false)
#5 /home/suburban/public_html/sys/lib/pkp/classes/core/Dispatcher.inc.ph in /home/suburban/public_html/sys/plugins/generic/htmlArticleGalley/HtmlArticleGalleyPlugin.inc.php on line 177
Thank you in advance for your kind help!