Error on upgrade product

[leadsoft]

Hello, I have 2 products on my site (Trial and 1 month subscription)

On my products/services i have option for trial to upgrade on subscription.

I choose to upgrade and i got this error : "

Oops!

Something went wrong and we couldn't process your request.

"

This is the error from error log: FastCGI sent in stderr: "PHP message: [WHMCS Application] ERROR: Error: [] operator not supported for strings in /var/www/nknebel/data/www/strimo.co.uk/includes/upgradefunctions.php:0 Stack trace: #0 /var/www/nknebel/data/www/strimo.co.uk/upgrade.php(0)

I have whmcs version 7.7.1 and PHP 7.3.4

Could you help me, please ? 

Thanks!

[brian!]

Hi @leadsoft

On 25/06/2019 at 09:17, leadsoft said:

Could you help me, please ?  

I would suggest trying either of these 3 things - doesn't matter about the order you try them...

1. is it a viable option to switch to an older version of PHP, e.g PHP7.3, 7.2 or earlier? Although v7.7 is supposedly compatible with PHP7.3, PHP 7.3.4 was released after the last WHMCS update in February 2019, so perhaps a feature that WHMCS is trying to use is no longer available, or used in a different way - possibly using an older PHP version will get this working until the next WHMCS production update (which I think we can safely say won't reach GA status until the end of July at the earliest now).
2. try switching your template from your custom to Six and see if the error still occurs.... this doesn't feel like a template issue, but it'a always worth ruling it out as a possible cause.
3. you could enable Error Reporting and that might give you some further details as to the cause.

[fwc]

I am not an experienced WHMCS user but I am learning.  From what I can tell,  you could change the PHP MyAdmin settings to edit certain variable strings to make sure they match your websites location on the server.  If this is bad advice, please someone point it out.