Hi,
It looks like the issue isn’t with Odoo itself but with the 
server environment. Since the PDF works locally but crashes on the 
server, it’s likely related to resource limits or dependencies. Here’s a
 structured approach:
Check Server Logs – Look at the system logs
 (/var/log/syslog, /var/log/messages) and Odoo logs to see what causes 
the crash (e.g., memory error, segmentation fault, or Python exception).
Memory
 / CPU Limits – PDFs with images or watermarks are heavier to process. 
The server might run out of memory. Check: RAM usage during upload, Swap
 space, Any ulimit restrictions
Dependencies / Libraries – Odoo 
Sign relies on libraries like PyPDF2, reportlab, or wkhtmltopdf. Ensure 
the server has the same versions installed as your local machine.
File
 Size / Timeout – If the PDF is large or contains many images, adjust: 
limit_request in Odoo config, proxy_read_timeout or proxy_send_timeout 
if behind Nginx/Apache
Compare Python Environment – Check if the 
server Python environment matches local (Python version, pip packages). 
Sometimes a missing or different library version can crash the process.
Test
 Minimal File – Try uploading a smaller PDF with a watermark to isolate 
whether it’s a file-specific issue or general PDF processing problem.
Hope it helps.
Thanks so much,
I also added this lines in the 2 files,
odoo18.conf: limit_request = 8192
/etc/nginx/sites-enabled/app.conf:
client_max_body_size 50M;
proxy_read_timeout 600s;
proxy_send_timeout 600s;
Now it's working,
Thanks Again.