Q1 ) I was trying to Browser import a classification (well within 1 MB) but I got the following error :
Could this be due to that fact that my file format is not correct ? Is there a way to valudate the classification file before upload?
Q2 ) I made some changes to the file, and import again but navigated away from the import page and now I can't track the status of browser import, is there a way to track it? (Did not put email notification or download file when import completes)
Q1) You need to use a tab-separated values (TSV) file. Excel can save this for you. The only way to validate a Classifications file is by doing so manually. I don't know of any online tool that validate it for you automatically.
Q2) Unfortunately, there's no other way to track an import. You can import your file again, then make sure to stay on that page until it reloads.
As mentioned below there are limitations on pre checking as its more ensuring you use correct template, and tool(excel) to maintain clean imports.
Having said that I think in your case its nothing more than file corruption and possible save settings from excel..
Use a text editor that allows you to look for invisible characters that may be added once you resave from excel.
Also remember to check overwrite data on web import as that can help avoid any errors.