Was going through the ajax request. Below is the error I have got
TemplateFile: SQLSTATE[HY000]: General error: could not call class constructor
#0 /var/www/ProcessWire/wire/core/Pages.php(0): PDOStatement->fetchObject()
#1 /var/www/ProcessWire/wire/core/Pages.php(229): Pages->getById(Array, Array)
#2 [internal function]: Pages->___find('parent_id=1, st...', Array)
#3 /var/www/ProcessWire/wire/core/Wire.php(365): call_user_func_array(Array, Array)
#4 /var/www/ProcessWire/wire/core/Wire.php(320): Wire->runHooks('find', Array)
#5 /var/www/ProcessWire/wire/core/PageTraversal.php(78): Wire->__call('find', Array)
#6 /var/www/ProcessWire/wire/core/PageTraversal.php(78): Pages->find('parent_id=1, st...', Array)
#7 /var/www/ProcessWire/wire/core/Page.php(1033): PageTraversal->children(Object(Page), 'start=0, limit=...', Array)
#8 /var/www/ProcessWire/wire/modules/Process/ProcessPageList/ProcessPageList.module(178): Page->children('start=0, limit=...')
#9 [internal function]: ProcessPageList->___find('start=0, limit=...', Object(Page))
#10 /var/www/ProcessWire/wire/core/Wire.php(365): call_user_func_array(Array, Array)
#11 /var/www/ProcessWire/wire/core/Wire.php(320): Wire->runHooks('find', Array)
#12 /var/www/ProcessWire/wire/modules/Process/ProcessPageList/ProcessPageList.module(165): Wire->__call('find', Array)
#13 /var/www/ProcessWire/wire/modules/Process/ProcessPageList/ProcessPageList.module(165): ProcessPageList->find('start=0, limit=...', Object(Page))
#14 /var/www/ProcessWire/wire/modules/Process/ProcessPageList/ProcessPageList.module(109): ProcessPageList->render()
#15 [internal function]: ProcessPageList->___execute()
#16 /var/www/ProcessWire/wire/core/Wire.php(365): call_user_func_array(Array, Array)
#17 /var/www/ProcessWire/wire/core/Wire.php(320): Wire->runHooks('execute', Array)
#18 /var/www/ProcessWire/wire/core/ProcessController.php(213): Wire->__call('execute', Array)
#19 /var/www/ProcessWire/wire/core/ProcessController.php(213): ProcessPageList->execute()
#20 [internal function]: ProcessController->___execute()
#21 /var/www/ProcessWire/wire/core/Wire.php(365): call_user_func_array(Array, Array)
#22 /var/www/ProcessWire/wire/core/Wire.php(320): Wire->runHooks('execute', Array)
#23 /var/www/ProcessWire/wire/core/admin.php(85): Wire->__call('execute', Array)
#24 /var/www/ProcessWire/wire/core/admin.php(85): ProcessController->execute()
#25 /var/www/ProcessWire/site/modules/AdminThemeThinktag/controller.php(13): require('/var/www/Proces...')
#26 /var/www/ProcessWire/site/templates/admin.php(13): require('/var/www/Proces...')
#27 /var/www/ProcessWire/wire/core/TemplateFile.php(169): require('/var/www/Proces...')
#28 [internal function]: TemplateFile->___render()
#29 /var/www/ProcessWire/wire/core/Wire.php(365): call_user_func_array(Array, Array)
#30 /var/www/ProcessWire/wire/core/Wire.php(320): Wire->runHooks('render', Array)
#31 /var/www/ProcessWire/wire/modules/PageRender.module(356): Wire->__call('render', Array)
#32 /var/www/ProcessWire/wire/modules/PageRender.module(356): TemplateFile->render()
#33 [internal function]: PageRender->___renderPage(Object(HookEvent))
#34 /var/www/ProcessWire/wire/core/Wire.php(365): call_user_func_array(Array, Array)
#35 /var/www/ProcessWire/wire/core/Wire.php(320): Wire->runHooks('renderPage', Array)
#36 /var/www/ProcessWire/wire/core/Wire.php(387): Wire->__call('renderPage', Array)
#37 /var/www/ProcessWire/wire/core/Wire.php(387): PageRender->renderPage(Object(HookEvent))
#38 /var/www/ProcessWire/wire/core/Wire.php(320): Wire->runHooks('render', Array)
#39 /var/www/ProcessWire/wire/modules/Process/ProcessPageView.module(172): Wire->__call('render', Array)
#40 /var/www/ProcessWire/wire/modules/Process/ProcessPageView.module(172): Page->render()
#41 [internal function]: ProcessPageView->___execute()
#42 /var/www/ProcessWire/wire/core/Wire.php(365): call_user_func_array(Array, Array)
#43 /var/www/ProcessWire/wire/core/Wire.php(320): Wire->runHooks('execute', Array)
#44 /var/www/ProcessWire/index.php(195): Wire->__call('execute', Array)
#45 /var/www/ProcessWire/index.php(195): ProcessPageView->execute()
#46 {main}