> Use when debugging hooks.py errors in Frappe/ERPNext. Covers hook not firing (typo, wrong dict structure), circular imports, app_include_js path errors, scheduler_events not running, doc_events on wrong DocType, permission_query_conditions SQL errors, override_doctype_class import failures, extend_doctype_class [v16+] conflicts, fixtures not loading. Error diagnosis by hook type for v14/v15/v16. doc_events error, circular import, fixtures error, override class error.
npx skills add https://github.com/Impertio-Studio/Frappe_Claude_Skill_Package --skill frappe-errors-hooks
Cross-ref: frappe-syntax-hooks (syntax), frappe-impl-hooks (workflows), frappe-errors-controllers (controller errors).
| Error / Symptom | Cause | Fix |
|-----------------|-------|-----|
| Hook not firing at all | Typo in dotted path | Verify module path matches actual file location |
| ImportError on bench start | Wrong module path or circular import | Fix import path; break circular dependency |
| AttributeError: module has no attribute | Function name typo in hooks.py | Match function name exactly to Python definition |
| app_include_js not loading | Path missing assets/ prefix or wrong extension | Use "assets/myapp/js/file.js" format |
| scheduler_events not running | Scheduler disabled or workers down | bench scheduler enable, check bench doctor |
| doc_events handler never called | DocType name misspelled in dict key | Use exact DocType name with spaces: "Sales Invoice" |
| permission_query_conditions breaks list view | SQL syntax error or frappe.throw() in handler | Return valid SQL string; NEVER throw |
| override_doctype_class import failure | Parent class import path changed between versions | Pin import to correct module path for target version |
| extend_doctype_class [v16+] method conflict | Two extensions define same method name | Rename conflicting methods; check hook resolution order |
| Fixtures not loading on install | Wrong dt key or DocType doesn't exist on target | Verify DocType exists before export; check filter syntax |
| extend_bootinfo breaks login | Unhandled exception in boot handler | Wrap ALL bootinfo code in try/except |
| Wildcard "*" handler breaks all saves | Unhandled exception in wildcard doc_events | ALWAYS wrap wildcard handlers in try/except |
| Hook fires but changes lost | Missing frappe.db.commit() in scheduler | Add explicit commit in scheduler/background tasks |
| Multiple handler chain broken | First handler throws, others never run | Isolate non-critical ops in try/except |
IS YOUR HOOK NOT FIRING?
│
├─► Check 1: Is the dotted path correct?
│ hooks.py: "myapp.events.sales.validate"
│ File: myapp/events/sales.py → def validate(doc, method=None):
│ COMMON MISTAKE: "myapp.events.sales_invoice.validate" when file is sales.py
│
├─► Check 2: Is the dict structure correct?
│ doc_events uses NESTED dict: {"Sales Invoice": {"validate": "path"}}
│ scheduler_events uses LIST: {"daily": ["path1", "path2"]}
│ permission_query uses FLAT dict: {"Sales Invoice": "path"}
│
├─► Check 3: Is bench restarted after hooks.py change?
│ ALWAYS run: bench restart (or bench clear-cache for dev)
│
├─► Check 4: Is the DocType name exact?
│ "Sales Invoice" NOT "SalesInvoice" NOT "sales_invoice"
│ Use exact DocType name as shown in Frappe UI
│
└─► Check 5: Is the app installed on the site?
bench --site mysite list-apps
# ❌ CAUSES ImportError — circular dependency
# myapp/hooks.py imports from myapp.events
# myapp/events/sales.py imports from myapp.hooks
# ✅ CORRECT — break the cycle
# Move shared constants to myapp/constants.py
# Import from constants in both hooks.py and events/
Rule: NEVER import from hooks.py in your event handlers. hooks.py is read by the framework, not imported by your code.
# ❌ WRONG — doc_events needs nested dict, not flat
doc_events = {
"Sales Invoice": "myapp.events.validate" # WRONG: string, not dict
}
# ✅ CORRECT
doc_events = {
"Sales Invoice": {
"validate": "myapp.events.sales.validate"
}
}
# ❌ WRONG — scheduler_events daily needs list
scheduler_events = {
"daily": "myapp.tasks.daily_sync" # WRONG: string, not list
}
# ✅ CORRECT
scheduler_events = {
"daily": ["myapp.tasks.daily_sync"]
}
# ❌ WRONG — cron needs nested dict with list values
scheduler_events = {
"cron": ["0 9 * * *", "myapp.tasks.morning"] # WRONG structure
}
# ✅ CORRECT
scheduler_events = {
"cron": {
"0 9 * * 1-5": ["myapp.tasks.morning_report"]
}
}
# ❌ WRONG — missing assets/ prefix
app_include_js = "js/myapp.js"
# ❌ WRONG — using Python module path instead of file path
app_include_js = "myapp.public.js.myapp"
# ✅ CORRECT — full asset path
app_include_js = "assets/myapp/js/myapp.js"
# ✅ CORRECT — multiple files as list
app_include_js = ["assets/myapp/js/app.js", "assets/myapp/js/utils.js"]
app_include_css = "assets/myapp/css/myapp.css"
Diagnosis: If JS/CSS not loading, check browser DevTools Network tab for 404. Run bench build after adding new files. ALWAYS verify the file exists at myapp/public/js/myapp.js.
# Step 1: Is scheduler enabled?
bench scheduler status
# If disabled: bench scheduler enable
# Step 2: Are workers running?
bench doctor
# Look for: "Workers online: X"
# If 0: bench start (dev) or supervisorctl restart all (prod)
# Step 3: Check Scheduled Job Log
# In Frappe UI: /api/method/frappe.client.get_list?doctype=Scheduled Job Log&limit=5
# Step 4: Check Error Log for task failures
# In Frappe UI: /app/error-log
# Step 5: Is the task registered?
bench execute frappe.utils.scheduler.get_all_tasks
# ❌ PROBLEM: Task runs but changes not persisted
def daily_sync():
for item in frappe.get_all("Item", limit=100):
frappe.db.set_value("Item", item.name, "synced", 1)
# MISSING: frappe.db.commit() — ALL changes lost!
# ✅ FIX: ALWAYS commit in scheduler tasks
def daily_sync():
for item in frappe.get_all("Item", limit=100):
frappe.db.set_value("Item", item.name, "synced", 1)
frappe.db.commit()
# ❌ PROBLEM: Task fails silently — no debugging possible
def daily_task():
try:
process_records()
except Exception:
pass # Silent death
# ✅ FIX: ALWAYS log errors in scheduler
def daily_task():
try:
process_records()
frappe.db.commit()
except Exception:
frappe.log_error(frappe.get_traceback(), "Daily Task Error")
| Event | Throw Effect | Transaction | Pattern |
|-------|-------------|-------------|---------|
| validate | Prevents save, full rollback | Pre-write | Collect errors, throw once |
| before_save | Prevents save, full rollback | Pre-write | Same as validate |
| on_update | Doc already saved, error shown | Post-write | Isolate non-critical ops |
| after_insert | Doc already saved, error shown | Post-write | Isolate non-critical ops |
| on_submit | Doc already submitted | Post-write | Isolate non-critical ops |
| on_cancel | Doc already cancelled | Post-write | Isolate non-critical ops |
# If App A and App B both register validate for Sales Invoice:
# App A's handler throws → App B's handler NEVER runs
# ✅ ALWAYS be aware: your handler is not alone
def validate(doc, method=None):
"""Collect errors, throw once at end."""
errors = []
if doc.grand_total < 0:
errors.append(_("Total cannot be negative"))
if errors:
frappe.throw("<br>".join(errors))
# ✅ For on_update: isolate independent operations
def on_update(doc, method=None):
try:
send_notification(doc)
except Exception:
frappe.log_error(frappe.get_traceback(), f"Notify error: {doc.name}")
try:
sync_external(doc)
except Exception:
frappe.log_error(frappe.get_traceback(), f"Sync error: {doc.name}")
# ❌ BREAKS transaction management
def on_update(doc, method=None):
frappe.db.set_value("Counter", "main", "count", 100)
frappe.db.commit() # Partial commit — dangerous!
# ✅ Framework handles commits automatically
def on_update(doc, method=None):
frappe.db.set_value("Counter", "main", "count", 100)
# ❌ BREAKS list view entirely
def query_conditions(user):
if "Sales User" not in frappe.get_roles(user):
frappe.throw("Access denied") # LIST VIEW CRASHES
return f"owner = '{user}'" # Also: SQL injection!
# ✅ CORRECT — safe fallback, escaped values
def query_conditions(user):
try:
user = user or frappe.session.user
if "System Manager" in frappe.get_roles(user):
return ""
return f"`tabSales Invoice`.owner = {frappe.db.escape(user)}"
except Exception:
frappe.log_error(frappe.get_traceback(), "Query Conditions Error")
return f"`tabSales Invoice`.owner = {frappe.db.escape(frappe.session.user)}"
Note: permission_query_conditions only affects frappe.db.get_list(), NOT frappe.db.get_all().
# ❌ BREAKS document access
def has_permission(doc, user=None, permission_type=None):
if doc.status == "Locked":
frappe.throw("Locked") # DOCUMENT INACCESSIBLE
# ✅ Return False to deny, None to defer
def has_permission(doc, user=None, permission_type=None):
try:
user = user or frappe.session.user
if doc.status == "Locked" and permission_type == "write":
return False
return None # Defer to default permission system
except Exception:
frappe.log_error(frappe.get_traceback(), "Permission Error")
return None
# ❌ COMMON: Import path changes between ERPNext versions
# v14 path:
override_doctype_class = {
"Sales Invoice": "myapp.overrides.CustomSI"
}
# myapp/overrides.py:
from erpnext.accounts.doctype.sales_invoice.sales_invoice import SalesInvoice
# This path may change in v15/v16!
# ✅ ALWAYS call super(), re-raise validation errors
class CustomSalesInvoice(SalesInvoice):
def validate(self):
try:
super().validate()
except frappe.ValidationError:
raise # ALWAYS re-raise validation errors
except Exception:
frappe.log_error(frappe.get_traceback(), "Parent validate error")
raise
self.custom_validation()
Warning: Only ONE app's override_doctype_class is active per DocType ("last writer wins"). Use extend_doctype_class [v16+] for multi-app compatibility.
# hooks.py
extend_doctype_class = {
"Sales Invoice": ["myapp.extensions.si.SalesInvoiceMixin"]
}
# ❌ CONFLICT: Two extensions define same method
# App A: class Mixin: def custom_calc(self): ...
# App B: class Mixin: def custom_calc(self): ...
# Result: Last app's method wins silently
# ✅ ALWAYS prefix method names with app name
class SalesInvoiceMixin:
def myapp_custom_calc(self):
"""Prefixed to avoid conflicts with other extensions."""
pass
# ❌ BREAKS LOGIN — unhandled error prevents desk from loading
def extend_boot(bootinfo):
settings = frappe.get_single("My Settings") # DoesNotExistError!
bootinfo.config = settings.config
# ✅ ALWAYS wrap in try/except with safe defaults
def extend_boot(bootinfo):
bootinfo.myapp_config = {}
try:
if frappe.db.exists("My Settings", "My Settings"):
settings = frappe.get_single("My Settings")
bootinfo.myapp_config = {"feature": settings.feature or False}
except Exception:
frappe.log_error(frappe.get_traceback(), "Bootinfo Error")
# ❌ WRONG — dt key misspelled
fixtures = [{"doctype": "Custom Field", "filters": [...]}] # "doctype" not "dt"!
# ✅ CORRECT — use "dt" key
fixtures = [{"dt": "Custom Field", "filters": [["module", "=", "My App"]]}]
# ❌ PROBLEM: DocType doesn't exist on target site
fixtures = [{"dt": "My Custom DocType"}] # If not created yet → install fails
# ✅ FIX: Ensure DocType is created before fixtures are imported
# Order: DocType JSON → fixtures JSON (install order matters)
Export command: bench --site mysite export-fixtures
Import: Automatic during bench --site mysite install-app myapp
frappe.db.commit() in scheduler — no auto-commitsuper() in override classes — re-raise ValidationErrorextend_bootinfo in try/except — errors break login"*" doc_events in try/except — errors break ALL savespermission_query_conditions — breaks list viewshas_permission — breaks document access| Hook Type | Can Throw? | Commit? | Error Strategy |
|-----------|:----------:|:-------:|----------------|
| doc_events (validate) | YES | NEVER | Collect errors, throw once |
| doc_events (on_update+) | Careful | NEVER | Isolate non-critical ops |
| scheduler_events | Pointless | ALWAYS | try/except + log_error |
| permission_query_conditions | NEVER | NEVER | Return "" or owner filter |
| has_permission | NEVER | NEVER | Return None on error |
| extend_bootinfo | NEVER | NEVER | try/except + safe defaults |
| override_doctype_class | YES | NEVER | super() + re-raise |
| extend_doctype_class [v16+] | YES | NEVER | Prefix methods, avoid conflicts |
| fixtures | N/A | N/A | Verify dt key and DocType existence |
| app_include_js/css | N/A | N/A | Check assets/ prefix, run bench build |
| File | Contents |
|------|----------|
| references/patterns.md | Complete error handling patterns by hook type |
| references/examples.md | Full working examples with error handling |
| references/anti-patterns.md | Common mistakes with wrong/correct pairs |
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Take impertio-studio/frappe-errors-hooks from the repository into ~/.claude/skills for personal
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