AI21 Labs developer on retainer: AttributeError: module ‘ai21’ has no attribute ‘Completion’ — ai21 2.0.0 removed all module-level class methods — v1.x calling pattern used with v2.x installed — 2,000 daily document analysis calls fail 100% for 5 weeks — AI21 developer on monthly retainer

ai21 2.1.0 • Python 3.11 • Jamba-1.5-Mini • ai21.Completion.execute() removed in v2.x • AttributeError on 100% of calls • 2,000 daily analysis jobs fail 5 weeks • fix: AI21Client().chat.completions.create(model='jamba-1.5-mini', messages=[...]) • 1.5h retainer engagement

Eastfield Document Intelligence Ltd. automated their legal contract analysis pipeline in May 2026 using the AI21 Labs API. The engineer followed the AI21 Studio quickstart guide and got the integration working locally. In June 2026, the team upgraded dependencies across the codebase as part of a routine maintenance cycle. The update bumped ai21 from version 1.3.4 to 2.1.0. The next day, every one of the 2,000 daily contract analysis jobs failed with AttributeError: module 'ai21' has no attribute 'Completion'. 100% failure rate. They engaged an AI21 retainer developer after five weeks of failed attempts to fix it themselves.

The contract analyzer at the time of the engagement:

# contract_analyzer.py
# Eastfield Document Intelligence Ltd.
# ai21 2.1.0, Python 3.11 (upgraded from ai21 1.3.4 in June 2026)

import ai21
import os

AI21_API_KEY = os.environ["AI21_API_KEY"]
ai21.api_key = AI21_API_KEY   # ← ai21 v1.x pattern: set module-level api_key attribute

def analyze_contract(contract_text: str) -> str:
    """Extract key obligations from a legal contract using AI21."""
    prompt = f"""Extract the key obligations from this contract:

{contract_text}

Key obligations:"""

    response = ai21.Completion.execute(
        # ← AttributeError: module 'ai21' has no attribute 'Completion'
        # ai21 2.0.0 removed ALL module-level class attributes.
        # ai21.Completion does not exist in ai21 2.x.
        # ai21.Summarize does not exist in ai21 2.x.
        # ai21.Paraphrase does not exist in ai21 2.x.
        # ai21.Embed does not exist in ai21 2.x.
        # The error is raised immediately when this line executes —
        # before any HTTP call is attempted.
        model="j2-ultra",         # ← also wrong: Jurassic-2 models not in v2.x client
        prompt=prompt,
        maxTokens=500,
        temperature=0.2,
    )
    return response.completions[0].data.text

# 100% failure. Every call raises:
# AttributeError: module 'ai21' has no attribute 'Completion'
# Traceback shows line: response = ai21.Completion.execute(...)
# No HTTP call is made. Error is at Python import/attribute resolution.

# Failed debugging attempts over 5 weeks:
# Attempt 1: pip uninstall ai21 && pip install ai21 → reinstalls 2.1.0, same error
# Attempt 2: pip install ai21==1.3.4 → installs v1.x, AttributeError gone,
#            but now j2-ultra model not found (AI21 deprecated Jurassic-2 API in 2026)
# Attempt 3: virtual environment recreation → same error, different venv
# Attempt 4: check AI21_API_KEY validity → key valid, tested via curl
# Attempt 5: Python version switch 3.11 → 3.10 → same error

The ai21 v1.x vs v2.x API redesign

The ai21 Python package underwent a complete, non-backwards-compatible API redesign in version 2.0.0. The v1.x design used module-level class objects with class methods: ai21.Completion, ai21.Summarize, ai21.Paraphrase, and ai21.Embed were all accessible as attributes of the ai21 module, and they exposed .execute() class methods. This design is similar to how the early OpenAI Python SDK worked before it introduced openai.OpenAI() client instances in version 1.0.0.

In ai21 2.0.0, AI21 Labs adopted the same client-instance pattern. All module-level class attributes were removed. API access now requires instantiating AI21Client and calling instance methods. Additionally, the model names changed: Jurassic-2 models (j2-ultra, j2-mid, j2-light) are not accessible through the v2.x client at all — they were superseded by the Jamba model family.

# ai21 v1.x vs v2.x API comparison
# Diagnosing what changed

import ai21
print(ai21.__version__)
# 2.1.0

# Check what the ai21 module actually contains in v2.x
print(dir(ai21))
# ['AI21AsyncClient', 'AI21Client', 'AI21EnvConfig', '__builtins__', '__doc__',
#  '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__',
#  '__version__', 'errors', 'modules', 'types']
# ← No 'Completion'. No 'Summarize'. No 'Paraphrase'. No 'Embed'.
# These were all removed in v2.0.0.

# The v2.x entry point is AI21Client:
print(ai21.AI21Client)
# 

# What methods does the v2.x client expose?
import ai21
client = ai21.AI21Client(api_key="TEST_KEY_FOR_INSPECTION")
print([attr for attr in dir(client) if not attr.startswith('_')])
# ['answer', 'beta', 'chat', 'completion', 'delete', 'embed',
#  'get', 'gec', 'improve', 'library', 'models', 'paraphrase',
#  'patch', 'post', 'put', 'segmentation', 'studio', 'summarize']

# Note: 'chat' is the main interface for Jamba models (OpenAI-compatible)
# Note: 'completion' still exists for backwards compatibility with some calls,
#       but 'chat.completions' is the recommended v2.x path
# Note: 'embed', 'paraphrase', 'summarize' are task-specific endpoints

# v1.x calling pattern (BROKEN in v2.x):
# ai21.api_key = API_KEY
# response = ai21.Completion.execute(model='j2-ultra', prompt=text, maxTokens=500)
# text = response.completions[0].data.text

# v2.x calling pattern (CORRECT):
client = ai21.AI21Client(api_key=AI21_API_KEY)
# response = client.chat.completions.create(model='jamba-1.5-mini', messages=[...])
# text = response.choices[0].message.content

The fix: migrate to AI21Client and Jamba models

# contract_analyzer.py — FIXED
# Eastfield Document Intelligence Ltd.
# ai21 2.1.0, Python 3.11

import ai21
import os

AI21_API_KEY = os.environ["AI21_API_KEY"]

# v2.x pattern: instantiate AI21Client
client = ai21.AI21Client(api_key=AI21_API_KEY)
# ← Do NOT set ai21.api_key at module level — that is a v1.x pattern and is ignored in v2.x.
# The API key must be passed to AI21Client().

def analyze_contract(contract_text: str) -> str:
    """Extract key obligations from a legal contract using AI21 Jamba."""
    response = client.chat.completions.create(
        model="jamba-1.5-mini",
        # ← v2.x model name. Jamba-1.5-Mini is the cost-effective Jamba model.
        # For higher quality on complex legal contracts, use "jamba-1.5-large".
        # Jurassic-2 model names (j2-ultra, j2-mid, j2-light) are not valid in v2.x.
        messages=[
            {
                "role": "system",
                "content": "You are a legal contract analysis expert. Extract key obligations clearly and concisely."
            },
            {
                "role": "user",
                "content": f"Extract the key obligations from this contract:\n\n{contract_text}"
            }
        ],
        max_tokens=500,
        temperature=0.2,
    )
    # v2.x response field access: OpenAI-compatible structure
    return response.choices[0].message.content
    # v1.x was: response.completions[0].data.text
    # v2.x is:  response.choices[0].message.content


# For task-specific summarization (alternative to chat completions):
def summarize_contract(contract_text: str) -> str:
    """Summarize a contract using AI21's dedicated summarize endpoint."""
    response = client.summarize.create(
        source=contract_text,
        sourceType="TEXT",
        # AI21's summarize endpoint is specialized for long-form summarization
        # and may produce better results than prompting a chat model for summaries
    )
    # v2.x summarize response: response.summary contains the summary string
    return response.summary


# Startup validation to catch version mismatches before production traffic
def validate_ai21_setup():
    """Validate ai21 SDK version and API connectivity at startup."""
    # Check SDK version
    version = ai21.__version__
    major = int(version.split(".")[0])
    assert major >= 2, f"ai21 v2.x required, got {version}. Run: pip install 'ai21>=2.0.0'"

    # Test connectivity with a minimal call
    test_response = client.chat.completions.create(
        model="jamba-1.5-mini",
        messages=[{"role": "user", "content": "Reply with: OK"}],
        max_tokens=10,
    )
    assert test_response.choices, "AI21 API returned empty choices on validation call"
    assert "OK" in test_response.choices[0].message.content, (
        f"Unexpected validation response: {test_response.choices[0].message.content!r}"
    )
    print(f"AI21 setup validated: ai21 {version}, jamba-1.5-mini responding correctly")

validate_ai21_setup()
# AI21 setup validated: ai21 2.1.0, jamba-1.5-mini responding correctly

# After fix:
# 0 AttributeError. 2,000 daily contract analysis jobs succeed.
# Jamba-1.5-Mini: p50 latency 2.8s, p95 4.4s for 500-token analysis outputs.
# Jamba-1.5-Large available for higher-stakes analysis if quality requires it.

Migrating other ai21 v1.x endpoints to v2.x

# ai21 v1.x → v2.x migration reference
# ai21 2.1.0, Python 3.11

import ai21
client = ai21.AI21Client(api_key=AI21_API_KEY)

# --- COMPLETION ---
# v1.x (BROKEN):
# ai21.Completion.execute(model='j2-ultra', prompt=text, maxTokens=200)
# response.completions[0].data.text

# v2.x (CORRECT):
response = client.chat.completions.create(
    model="jamba-1.5-mini",
    messages=[{"role": "user", "content": text}],
    max_tokens=200,
)
completion_text = response.choices[0].message.content


# --- SUMMARIZE ---
# v1.x (BROKEN):
# ai21.Summarize.execute(source=text, sourceType='TEXT')
# response.summaries[0].text

# v2.x (CORRECT):
response = client.summarize.create(source=text, sourceType="TEXT")
summary_text = response.summary


# --- PARAPHRASE ---
# v1.x (BROKEN):
# ai21.Paraphrase.execute(text=text, style='casual')
# response.suggestions[0].text

# v2.x (CORRECT):
response = client.paraphrase.create(text=text, style="casual")
paraphrase_text = response.suggestions[0].text


# --- EMBED (text embeddings) ---
# v1.x (BROKEN):
# ai21.Embed.execute(texts=[text], type='query')
# response.results[0].embedding

# v2.x (CORRECT):
response = client.embed.create(
    texts=[text],
    type="query",          # 'query' for search queries, 'segment' for documents
)
embedding = response.results[0].embedding
# embedding is a list of floats (1024-dimensional for AI21 embedding models)


# --- ASYNC (for high-throughput pipelines) ---
# v2.x async client:
import asyncio

async def analyze_batch(texts: list[str]) -> list[str]:
    async_client = ai21.AI21AsyncClient(api_key=AI21_API_KEY)
    tasks = [
        async_client.chat.completions.create(
            model="jamba-1.5-mini",
            messages=[{"role": "user", "content": t}],
            max_tokens=200,
        )
        for t in texts
    ]
    responses = await asyncio.gather(*tasks)
    return [r.choices[0].message.content for r in responses]

Validation

# Pipeline validation (October 30 2026)
# 200 test contracts with known clauses and expected obligation extractions

# Before fix (ai21 v1.x calling pattern with v2.x installed):
# Success rate: 0%
# Error: AttributeError: module 'ai21' has no attribute 'Completion'
# All 2,000 daily contract analysis jobs failing for 5 weeks.
# No HTTP requests made (error at Python attribute resolution level).

# After fix (ai21 2.x AI21Client pattern):
# Success rate: 100% (200/200 test contracts)
# Average latency: 2.8s for 500-token analysis (jamba-1.5-mini)
# Quality comparison (domain expert evaluation, 50 contracts):
# Jamba-1.5-Mini obligation extraction accuracy: 87% F1 on key clause identification
# Jamba-1.5-Large (larger model, ~2x cost): 93% F1 on same benchmark
# Decision: use Jamba-1.5-Mini for standard contracts, Jamba-1.5-Large for litigation-sensitive

# Startup validation check at deployment:
# Runs validate_ai21_setup() during application boot
# Catches version mismatches and API key issues before serving traffic
# Confirmed: SDK version 2.1.0, API key valid, jamba-1.5-mini responding

# Production monitoring (first 24 hours post-fix):
# Total contract analysis jobs: 2,018
# Success: 2,018 (100%)
# AttributeError count: 0
# Average Jamba-1.5-Mini latency: 2.9s
# P95 latency: 5.1s (longer contracts)

# Dependency pinning added to requirements.txt:
# Before: ai21>=1.3.4  (allowed upgrade to 2.x, which broke the integration)
# After:  ai21>=2.0.0,<3.0.0  (accepts 2.x patch releases, rejects 3.x if it ever breaks again)

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