CLion 2021.1 Help

File size and length limits

File size limit

For performance and memory consumption reasons, CLion sets the following file size limits:

  • The maximum size of files that CLion is able to open, controlled by the idea.max.content.load.filesize IDE property. Default value is 20000 kilobytes.

  • The maximum size of files that CLion provides code assistance for, controlled by the idea.max.intellisense.filesize property. Default value is 2500 kilobytes.

Change the file size limit

  1. Do one of the following:

    • Select Help | Edit Custom Properties from the main menu.

    • On the Welcome screen, click Configure and then select Edit Custom Properties.

    • If you cannot start CLion, you can manually create an empty file in the CLion configuration directory.

  2. In the custom file opened in a new editor tab, specify the values you want to change. For example,


    The properties you add to this file override the corresponding properties in the original default file.

File length limit

By default, the maximum C/C++ source/header file length in CLion is limited to 500 000 characters. If that limit is exceeded, all the code insight features, such as code completion and syntax highlighting are disabled. In this case the IDE notifies you about the current configured limit and the actual file length.

Change the file length limit in the Maximum File Length dialog

  1. Click the link in the upper right corner of the IDE notification: Maximum file length pop-up

  2. In the dialog that opens, specify the file length limit and press OK to proceed:

    The Maximum File Length dialog

Change the file length limit in the Registry

  1. Select Help | Find Action from the main menu or press Ctrl+Shift+A.

  2. Search for Registry and press Enter.

  3. In the dialog that opens, start typing cidr.max.intellisense.file.length. Specify the desired file size limit in the Value field. Click Close to proceed.

    Cl new file length registry
  4. Invalidate project symbols manually by calling File | Invalidate Caches / Restart.

Last modified: 08 March 2021