When you connect Feature.fm with Meta Ads, Meta Events Manager may display diagnostics or recommendations about your browser and server-side events.
These messages can look concerning, but a Meta diagnostic does not necessarily mean that Feature.fm is sending your event data incorrectly.
Meta evaluates your events against its own recommendations for event matching and attribution. Some of the information Meta recommends may not be available from a typical Feature.fm visitor, while other diagnostics are related to browser privacy settings, mobile networks, or how Meta processes event data.
This article explains the most common diagnostics and when you should contact Feature.fm versus Meta.
How Feature.fm sends events to Meta
Feature.fm can send event information to Meta through two paths:
- Browser events — sent through Meta Pixel running in the visitor's browser.
- Server events — sent through Meta's Conversions API (CAPI).
Some information, such as Meta's fbp and fbc identifiers, can be available to both paths.
Feature.fm passes these identifiers through our event pipeline without modifying them.
fbc / Click ID
The _fbc value is created by Meta's own Pixel. Feature.fm does not generate or modify this value.
When an _fbc value is available to Feature.fm, we pass it through our server-side event flow to Meta's Conversions API without changing it.
Meta may nevertheless display a diagnostic such as:
"Send fbc parameter for FeatureFM_pageview events"
This can happen when Meta sees an fbc value on a browser event but does not receive one on a corresponding server event.
There are several reasons this can happen without a problem in Feature.fm's event processing, including:
- The visitor does not have a current
_fbccookie. - The visitor returned to the page using a stale or expired cookie.
- Browser privacy features or ad blockers interfered with the cookie or
fbclid. - A redirect removed the
fbclidbefore the Pixel could establish the value. - Meta changes how it evaluates or validates
_fbcvalues.
Feature.fm does not modify, lowercase, truncate, or otherwise transform the fbc value.
If Meta reports that a small percentage of events are missing fbc, this does not by itself indicate that Feature.fm is dropping the parameter.
"Client IP addresses are associated with multiple users"
Meta may display a diagnostic stating that the same client IP address appears to be associated with multiple users.
This does not necessarily mean that Feature.fm is sending a shared server IP address.
Feature.fm sends the visitor's client IP address with server-side events. However, an IP address does not always identify one individual person.
For example, mobile carriers commonly use Carrier-Grade NAT (CGNAT), which allows many customers to access the internet through the same public IP address.
As a result, Meta may legitimately observe:
- Visitor A → IP address 123.45.67.89
- Visitor B → IP address 123.45.67.89
- Visitor C → IP address 123.45.67.89
This is a characteristic of the visitor's network, not necessarily a problem with Feature.fm's tracking.
What about IPv4 vs. IPv6?
Meta may also show different IP address formats between browser and server events.
A visitor's browser and network infrastructure can expose IPv4 or IPv6 addresses differently. Feature.fm cannot guarantee that the same visitor will appear with the identical IP representation in every context.
IP address is also only one of the signals Meta can use to match events.
fbp and fbc are important matching signals
Meta uses multiple signals to associate events with users.
Two important browser identifiers are:
-
fbp— the browser identifier created by Meta Pixel -
fbc— the identifier associated with a Meta ad click (fbclid)
When these identifiers are available, Feature.fm passes them through to Meta's server-side events.
Strong fbp and fbc coverage provides Meta with useful matching signals even when IP addresses are shared or other identifiers are unavailable.
Why is external_id showing 0%?
Feature.fm does not currently send an external_id with these server-side events.
This is expected and there is no setting you need to enable in your Feature.fm account.
Adding external_id would require a change to Feature.fm's server-side implementation.
If Meta recommends adding external_id, this is a recommendation from Meta rather than an indication that your Feature.fm configuration is incomplete.
Why are hashed email and name fields missing?
Meta may recommend sending hashed customer information, such as email addresses or names, to improve event matching.
However, Feature.fm can only send information that is actually collected from a visitor.
Most Feature.fm campaign landing pages do not require visitors to provide their name or email address. Therefore, low or zero coverage for these fields is expected.
Feature.fm does not have a visitor's email address or name simply because they clicked an advertisement or visited a Smart Link.
This means a diagnostic showing low coverage for these fields does not necessarily indicate missing or misconfigured data.
Does this affect Meta Ads performance?
Meta uses multiple signals when matching events and attributing conversions.
A diagnostic or recommendation does not automatically mean that your events cannot be attributed or that your campaigns are not working.
However, if you are seeing a significant and measurable change in attribution, audience size, or campaign performance along with evidence of missing or incorrect event data, that may warrant further investigation.
When should I contact Feature.fm?
Please contact Feature.fm if you have evidence of an actual event-delivery or data-integrity problem, such as:
- Server events are consistently missing rather than only occasionally missing a parameter.
-
fbporfbccoverage is unexpectedly or dramatically lower than normal. - Events are not reaching the correct Meta Pixel/Dataset.
- A parameter that Feature.fm sends appears to be changed or missing when received by Meta.
- Server events have stopped or dropped significantly.
- You can provide specific examples showing a discrepancy between what Feature.fm sends and what Meta receives.
When contacting us, please include:
- Your Meta Pixel/Dataset ID
- The event name
- The exact diagnostic message
- A screenshot of the diagnostic, if possible
- A few example events or the approximate timeframe when the issue occurred
This information allows us to determine whether there is an issue with Feature.fm's event delivery.
When should I contact Meta?
Meta is the best source for questions about:
- Meta's Event Match Quality scoring
- Meta's recommendations for additional parameters
- Why Meta is recommending the Parameter Builder
- How Meta evaluates IP addresses and matching
- Meta's attribution and audience-matching algorithms
- Changes to Meta's requirements or recommended event parameters
If Feature.fm has confirmed that a value is being passed through correctly, but Meta is still reporting a diagnostic about how that value is evaluated, Meta Support may be able to provide more detail about what their systems are expecting.
The bottom line
A Meta diagnostic is not automatically an indication that Feature.fm tracking is broken.
Feature.fm passes available Meta identifiers through to Meta without modifying them. Some information Meta recommends—such as external_id, names, or email addresses—is not currently available in the standard Feature.fm campaign experience.
Other diagnostics can result from normal internet and browser behavior, including shared public IP addresses, privacy protections, stale cookies, ad blockers, and redirects.
If there is evidence that Feature.fm is actually sending incorrect, missing, or misrouted event data, we're happy to investigate.