I have tried to export chart of accounts from an excel file and system raised raised several errors which when resolved the system froze

Good to see you here, jsmukasa-imprint.

We have to make sure that you're using a supported browser. I suggest Google Chrome, Mozilla Firefox, or Microsoft Edge. Please update them because older versions can result in some issues.

Also, you can export the file through an incognito window. If this error continues, you may clear the cache cause it's also one of the reasons why we encounter errors in QuickBooks.

Then, export the file again.

1. Go to the Reports menu.
2. Search for Account List.
3. Select the Export icon, then choose Export to Excel.

Additionally, please update it if you're using the QuickBooks Online app for desktop. If this behavior persists, you can also 

clear cache in the QuickBooks app.

1. Select Help.
2. Choose Reset App Data.

Please post again if you need more help. I'll be here!