Fail-Loud Defaults

PraisonAI raises clear errors instead of silently picking a default when configuration is ambiguous

PraisonAI raises clear errors instead of silently picking a default when configuration is ambiguous.

from praisonaiagents import Agent

# Explicit provider/model — no silent OpenAI fallback
agent = Agent(name="assistant", llm="ollama/llama3")
agent.start("Hello!")

The user passes ambiguous configuration; PraisonAI raises an explicit error with a fix hint instead of silently falling back.

How It Works

Behaviour change (PR #2122): Several subsystems that previously fell back silently now raise explicit errors. Review the table below when upgrading.

What Changed

Area	Old behaviour	New behaviour	Deep dive
Database URL	Unknown scheme → SQLite fallback	ValueError	Cloud Databases
Model string	Unrecognised name → OpenAI	ValueError	Multi-Provider Advanced
Daytona sandbox	Appeared available with client	NotImplementedError	Sandbox
LazyCache	Cached None on ImportError	Re-raises ImportError	Optional deps docs
Approval	enabled: false by default	enabled: true by default	Approval
Claude CLI backend	bypassPermissions default	default mode; bypass requires opt-in	CLI Backend Protocol
SandlockSandbox (PR #1367)	Landlock ABI too low → silent SubprocessSandbox fallback	RuntimeError at init time	Sandbox

Quick Start

1. Grep your logs for new errors

   grep -r "Unable to infer DB backend\|Cannot infer provider\|Daytona backend not yet implemented" logs/
   
2. Fix database URLs explicitly

   # Was silently SQLite — now raises ValueError
   db_url = "sqlite:///mydata.db"  # explicit scheme required
   
3. Use provider/model form

   from praisonaiagents import Agent
   
   # Was OpenAI fallback — now raises ValueError
   agent = Agent(name="assistant", llm="ollama/llama3")
   

Migrating

Exception text	Fix
Unable to infer DB backend from URL '...'; supported schemes: postgres://, mysql://, sqlite://, redis://, libsql://, http(s)://	Prefix URL with a supported scheme, e.g. sqlite:///path.db
Cannot infer provider from model '...'. Use the 'provider/model' form, e.g. 'ollama/llama3', 'bedrock/anthropic.claude-3-sonnet'.	Use provider/model or a recognised prefix (gpt-, claude-, gemini-)
Daytona backend not yet implemented. Use 'subprocess', 'docker', or 'e2b' sandbox instead.	Switch sandbox_type to a supported backend
Approval prompts where none expected	Set approval=False or approval: {enabled: false} in YAML

Best Practices

Prefer explicit configuration

When in doubt, spell out schemes, provider prefixes, and backend names — silent fallbacks are gone.

Disable approval only when intended

Approval is on by default (PR #2122). Use approval=False for fully autonomous runs.

Never use BYPASS without env gate

Claude Code bypass requires unsafe=True and PRAISONAI_CLAUDE_BYPASS_PERMISSIONS=1.

Pin sandbox backends explicitly

Do not rely on implicit fallbacks — set sandbox_type to a supported backend (subprocess, docker, or e2b).

Related

Approval

Safe-by-default approval gates

Cloud Databases

Supported DB URL schemes