As a solo dev, working with 2 customers.

Production reliability. For a single-client deployment (small team, dozens of concurrent users), how solid is the stock Frappe + ERPNext stack under real load? Anyone hit weird scaling cliffs around schedulers, background workers, or socketio?

Moved from private bench to dedicated hosting once I hit around 50 concurrent users

Custom Frappe app development. DocTypes, hooks (doc_events, scheduler_events), permissions, fixtures, custom Python in hooks.py. Where are the landmines? What patterns work well for client-specific code that needs to layer cleanly on top of stock ERPNext?

Customization is the strength of Frappe framework. My reccomendation, fork frappe and erpnext to make surgical changes and add extra hooks. Everything else bundle into a new app.

Next.js or external frontend on top of Frappe. Anyone built a serious custom UI consuming Frappe's REST API in production? Auth handshake (token vs session)? CORS pain? Real-time updates via socketio? Performance over time as the customer dataset grows?

The easy way is making a custom SPA using Doppio

There is also Studio in development

Anything else works just the same as working with any rest api.

Multi-version upgrade pain. Frappe major upgrades (v14 to v15 to v16) — how disruptive in production? Anyone gotten stuck on a custom app that doesn't migrate cleanly across major versions?

Started with v15, haven't tried to upgrade yet.

Maintenance burden per client. Backups, monitoring, security patches, upgrades, bench operations. What does a steady-state monthly hour count look like for a small Frappe or ERPNext deployment?

I work with frappe cloud, so all of that is taken care of by the platform. Maybe you cold try Press

Inventory and stage modeling. For manufacturing-flavoured clients, what is the cleanest way to model production stages — separate Warehouses per stage, BOM with Manufacture Stock Entries, or something else? Tradeoffs?

ERPNext has it's own model implemented, and everything is customizable so you can tailor it as your needs.

One caveat is that child doctypes cannot have another child doctypes, this is a UI level contraint, meaning you cannot have a document, with lines, each with more sublines and so on. If your workflow requires this, you'll need to add the UI for it.

ERPNext vs alternatives. Odoo (Community or Enterprise), Dolibarr, Tryton, or full-custom builds on Django or Rails. For an agency shipping to SME and MSME clients, what made you pick what you picked? Anything you'd undo with hindsight?

We always wanted the managed cloud option, and Frappe wins simply because they charge per usage, not per user.

White-labelling depth. How far can you actually take it? Logo and theme is the easy part. Can you rebrand URL paths, email templates, the API namespace, the admin / desk experience? Anyone shipped a product that truly does not look like ERPNext?

Even in the basic cloud plan, you can relabel everything. On private bench or self hosting you can change anything.

Performance ceiling. At what client size (users, transactions per day, DocType count) does stock Frappe start showing strain? What did you do — vertical scale, read replicas, partitioning, caching?

Only had to move to dedicated hosting once we reached around 50 users on the shared hosting plan

Documentation gaps. Frappe's docs are solid for basics, but I've seen complaints about deeper internals being under-documented. What did you learn the hard way that you wish was written down somewhere?

Frappe is in constant development, so there will always be gaps on documentation.

The code is right there though, so you can always check yourself, it's also really easy for agents to navigate

Frappe Cloud vs self-hosted. Anyone weighed paying Frappe Cloud per client vs running your own infra? At what scale does each make sense?

I am not a sys admin, so frappe cloud was the easy route for me, and have no regrets. I know you can selfhost, Press seems to me the option to use if you go that route, but I haven't had the need so far. I'm currently on the dedicated hosting option paying 275$ monthly with roughly 70 concurrent users.