According to Intuit, error code 20146 06636 is an error that can occur when running the Rebuild Data utility on a company file (.qbw) that had been converted from an older to a newer version. It indicates that the company file (.qbw) had possible data corruption before the file was converted to the newer version.
If possible, Intuit recommends returning to the file before it was converted to the newer version, repairing the damage, and re-converting to the newer version.
However, if the file had been converted some time ago, this solution isn’t practical.
For more information on this error, consult this Intuit knowledge base article.