Got the same type of error trying to import .xlsx file under none-administrator users, importing excel as administrator works fine, though. Did you find any solution? It seems that your problem is relevant to mine.

Here is my exception trace:
```

Uncaught SyntaxError: Unexpected token '<'

http://localhost:8069/web#action=import&cids=1&menu_id=98&model=account.move:1
Traceback:
SyntaxError: Unexpected token '<'
    at DOMEval (http://localhost:8069/web/content/311-a7d6acc/web.assets_common.js:709:10)
    at Function.globalEval (http://localhost:8069/web/content/311-a7d6acc/web.assets_common.js:723:41)
    at text script (http://localhost:8069/web/content/311-a7d6acc/web.assets_common.js:1325:466)
    at ajaxConvert (http://localhost:8069/web/content/311-a7d6acc/web.assets_common.js:1278:79)
    at done (http://localhost:8069/web/content/311-a7d6acc/web.assets_common.js:1308:10)
    at XMLHttpRequest.<anonymous> (http://localhost:8069/web/content/311-a7d6acc/web.assets_common.js:1324:314)
```

Update: the problem was odoo has some troubles with recognizing if file is .xlsx of .svg
https://github.com/odoo/odoo/pull/36081
Try to look closely at odoo logs, maybe you'll find something like "Only admins can upload SVG files." as I found.
Hope you'll find your solution.