Error codes below relate to TestNav auto updates:

Error NumberError MessageAdditional Info and Instruction
12001The update site URL is not correct. 
Contact Pearson Support.
12002The URL to the config file on the update site is not correct.
Contact Pearson Support.
12003The config file is corrupted.
Restart the application and then log in. If you cannot resolve this issue, contact Pearson Support.
12004The config file is corrupted.
Restart the application and then log in. If you cannot resolve this issue, contact Pearson Support.
12005The config file is corrupted.
Restart the application and then log in. If you cannot resolve this issue, contact Pearson Support.
12006The wrong config file was downloaded.
This error happens when the major version of the launcher (1.4 for example) does not match the major version in the config file (1.5 for example). Contact Pearson Support.
12007The update files on disk are either missing or have been corrupted.
Restart the application and then log in. If you cannot resolve this issue, contact Pearson Support.
12008The app does not have the necessary permissions to read or write to the directory where it will store update files.
Contact Pearson Support.
12009The app does not have the necessary permissions to delete from the directory where the update files are stored.
Contact Pearson Support.
12010There was an error downloading the update files.
Contact Pearson Support.
12011The app is unable to write to the location where we extract the update files.
Contact Pearson Support.
12012There was an error attempting to extract the update files.
Contact Pearson Support.
12013TestNav was unable to start.
Contact Pearson Support.

Tiny link: https://support.assessment.pearson.com/x/CwAqAQ