| Business Type | Benefit | |---------------|---------| | Agencies | Branded invoices with project breakdowns | | Subscription SaaS | Auto‑generated recurring invoices with usage-based items | | Freelancers | Quick switching between client‑specific tax & note templates | | Wholesale/Retail | Bulk invoice creation for repeat orders |

Enable Perfex’s debug mode:
define('APP_DEBUG', true); in application/config/config.php.
Then check /logs/index.php for module‑specific errors.

Perfex CRM is a powerful, open‑source customer relationship management system. Its native invoicing supports basic fields, items, taxes, and payment records. However, standard invoices may lack:

An Invoice Builder Module extends Perfex’s Invoice_model and view layers. It typically adds a drag‑and‑drop editor or a template manager that overrides the default PDF output (using libraries like dompdf or mPDF).

Even with a correctly named ZIP file, issues can arise.

| Error | Likely cause | Solution | |-------|--------------|----------| | Module upload fails | PHP max upload size too small | Increase upload_max_filesize and post_max_size in php.ini | | Class InvoiceBuilder not found | Module not placed in correct folder | Check /modules/invoice_builder/ exists with InvoiceBuilder.php | | Blank PDF output | Missing write permissions for cache/ | Set 755 or 775 recursively on module’s tmp/cache folder | | Invoice number duplicates | Custom numbering conflict with core | Disable core auto‑numbering in Settings → Invoices | | 404 when editing template | .htaccess rewrite conflicts | Add RewriteRule ^modules/(.*)$ - [L] in root .htaccess (contact host) |