Failed Ajax request or invalid JSON returned for file upload in copyediting

In the copyediting section, when you click on the Upload file link, you get the following error: Failed Ajax request or invalid JSON returned, for which a file cannot be uploaded. Thank you
Version Ojs
PHP log:
[03-Aug-2021 13:30:19 Asia/Kuwait] PHP Warning: Declaration of ManageFinalDraftFilesForm::execute($stageSubmissionFiles, $fileStage = NULL) should be compatible with ManageSubmissionFilesForm::execute($stageSubmissionFiles = NULL, $fileStage = NULL, …$functionArgs) in C:\inetpub\wwwroot\ingvojs\lib\pkp\controllers\grid\files\final\form\ on line 39