Crash Web

Good afternoon.
The OnlyOffice Web interface crashes periodically. Was treated by restarting the server. This happened the next time. Here is the error output.
Tell me what to do to solve this problem. Thank you in advance!

Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed (for security reasons).

Details: To enable the details of this specific error message to be viewable, please create a <customErrors> tag within a "web.config" configuration file located in the root directory of the current web application. This <customErrors> tag should then have its "mode" attribute set to "Off".

<!-- Web.Config Configuration File -->

<configuration>
    <system.web>
        <customErrors mode="Off"/>
    </system.web>
</configuration>

Notes: The current error page you are seeing can be replaced by a custom error page by modifying the "defaultRedirect" attribute of the application's <customErrors> configuration tag to point to a custom error page URL.

<!-- Web.Config Configuration File -->

<configuration>
    <system.web>
        <customErrors mode="RemoteOnly" defaultRedirect="mycustompage.htm"/>
    </system.web>
</configuration>
Version Information: 5.16.0.179 (tarball Thu Oct 4 10:29:10 UTC 2018); ASP.NET Version: 4.0.30319.42000

Hello,
please specify the version of Community Server and the type of installation of Workspace (docker or deb/rpm).

OnlyOffice Сommunity Server 9.6.3.691, Ubuntu 16.04.

9.6.3 was released more than 2 years ago, we cannot troubleshoot this version. I strongly recommend installing the latest version 11.5.4.
Use the installation script to install the update:

wget https://download.onlyoffice.com/install/install-Debian.sh
bash install-Debian.sh -u true

Note: make a snapshot of the server before installing the update to be able to quickly roll back if something goes wrong during the update.