How to open ONETOC2 files? 4 simple methods of solving such problems

When you encounter a problem with an unknown ONETOC2 file and you do not know how to open such file, the first step you should take is to determine the cause of given problem. We will show you how to address most common problems with ONETOC2 files and how to solve them in 4 simple steps.

ONETOC2 File Extension

  • File type Microsoft OneNote Table Of Contents Format
  • File developer Microsoft
  • File category Settings Files
  • File popularity rating
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How to open ONETOC2 file?

In some cases problems may occur when trying to open ONETOC2 files. Steps listed below can be helpful in addressing such problems.

Step 1 – Verify whether the file is properly associated with selected software

The first thing user should do is to associate application with ONETOC2 files. It may happen so that even when an application that supports ONETOC2 files is installed on the system it is not properly associated with this file format. This can be easily remedied by associating program with ONETOC2 files. In order to associate such files with given application, user must open the file menu (by right-clicking on the file) and choosing "Open with". A list of suggested applications will be displayed at the top part of menu. Next, select an application and confirm your choice by checking "Always use the selected application to open this kind of files" option. Confirm your selection by clicking OK.

In order to open ONETOC2 file, focus on steps 1 and 2


In majority of cases following instruction in step 1 and 2 should be enough to open files with ONETOC2 extension. Before attempting the next steps, test all the programs listed below.

Step 2 – Install a program that supports ONETOC2 files

Should it happen that the section with suggested programs is empty, it is most probable that no program supporting ONETOC2 files is installed on the system. Choose a program from the following list and install it:

Programs that support files with ONETOC2 extension

Step 3 – Check for other possible causes of errors

  • Corrupted storage medium on which the ONETOC2 file is stored
  • File data corruption or incompleteness (for example, due to incomplete download or copy process). In such case the file must be re-downloaded or properly copied and then opened again.
  • Compatibility issues – check whether ONETOC2 extension is compatible with user’s operating system
  • Administrative policy settings may prevent user from opening given file

Step 4 – Contact an expert

If you are still unable to open ONETOC2 file, you should contact an IT expert. You could also try to contact the developer of given software that supports ONETOC2 files. Appropriate website addresses can be found by clicking the name of given program in the list above.

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