By checking the error details from your server error logs and let us know the error details so that we can suggest. Please make sure that `MySQL` `only_full_group_by` mode is disabled.

If you can't find the server error logs, please check with your host. You can even enable app logs by changing `log_threshold` to `1` in `app/config/config.php` and the visit page again to reproduce error and it will be logged in later file in `app/logs/` folder.

I want to give all the information to log in to fix the problem. FTP etc.

ERROR - 2019-11-06 10:39:06 --> Severity: Parsing Error --> syntax error, unexpected 'class' (T_CLASS), expecting identifier (T_STRING) /home/baluna/domains/cms.baluna.ro/public_html/vendor/kwn/number-to-words/src/NumberToWords.php 46
ERROR - 2019-11-06 10:39:08 --> Severity: Parsing Error --> syntax error, unexpected 'class' (T_CLASS), expecting identifier (T_STRING) /home/baluna/domains/cms.baluna.ro/public_html/vendor/kwn/number-to-words/src/NumberToWords.php 46
ERROR - 2019-11-06 10:40:23 --> Severity: Parsing Error --> syntax error, unexpected 'class' (T_CLASS), expecting identifier (T_STRING) /home/baluna/domains/cms.baluna.ro/public_html/vendor/kwn/number-to-words/src/NumberToWords.php 46

I solved the problem. But when I want to download an invoice I get an error, error 500. At clients I can download pdfs. not to invoices

Please update to php 7.0 - 7.2 and if still have issues, check the error logs again and post the error details.

ERROR - 2019-11-06 21:42:33 --> Severity: error --> Exception: Call to undefined function Dompdf\mb_internal_encoding() /home/baluna/domains/cms.baluna.ro/public_html/vendor/dompdf/dompdf/src/Dompdf.php 274

Please install/enable `php-mbstring`

PHP Fatal error: Call to a member function num_rows() on boolean in /public_html/fac/app/libraries/Datatables.php on line 448

**[Oğuzhan Tülek](/u/oguzhantulek)** Please always post new question.

You can check the server requirements at [item page](https://tecdiary.net/products/simple-invoice-manager-invoicing-made-easy)