🔬 DETAILED TEST 1. Define the Bug Observed symptom The custom dashboard's customer-statistics section fails for Shop Manager users. Expected behavior Authorized Shop Manager users should receive the REST API response containing the statistics. Actual behavior The REST API returns: HTTP 403 Forbidden for Shop Manager users. Affected users Shop Manager: affected Administrator: not affected Other roles: not yet tested Affected functionality Only the customer-statistics API request is currently known to be affected. Reproducibility High. The provided evidence shows consistent role-dependent behavior. --- 2. 🧩 Facts vs Assumptions Confirmed facts The endpoint exists. The endpoint responds successfully for Administrators. The endpoint returns 403 for Shop Managers. The problem occurs at the REST API authorization layer. The permission-checking callback was recently modified. There is no PHP fatal error in the available logs. Unknown Exact implementation of the permission callback. Which capability the callback checks. Which capabilities the Shop Manager role actually possesses. Whether the endpoint uses a custom capability. Whether the callback checks the current user incorrectly. Whether a security plugin also modifies REST API authorization. Important distinction The 403 response is the symptom. The underlying cause is likely somewhere in the authorization decision that produces that 403. --- 3. 🔄 Failure Model The relevant execution flow is: 👤 Shop Manager logs in ↓ 🖥️ Custom Dashboard ↓ JavaScript fetch() ↓ 🌐 WordPress REST API ↓ Endpoint registration ↓ 🔐 permission_callback ↓ Capability / authorization check ↓ ❌ 403 Forbidden For an Administrator: 👤 Administrator ↓ REST API request ↓ permission_callback ↓ ✅ Authorization succeeds ↓ 📊 Customer statistics returned The important divergence is therefore likely at the authorization decision, not at the JavaScript request itself. --- 4. 🧠 Root-Cause Hypotheses Hypothesis A — Incorrect capability check Plausibility: Strong The recently modified permission callback may check a capability that Shop Managers do not possess. For example, conceptually: current_user_can( 'some_admin_only_capability' ) If Shop Managers do not have that capability, WordPress correctly rejects the request. Verification Inspect the endpoint's permission_callback and identify the exact capability being checked. Then compare that capability against the Shop Manager role. --- Hypothesis B — Permission callback incorrectly restricts by role Plausibility: Strong The developer may have implemented logic that explicitly allows only Administrators. For example, conceptually: if administrator → allow else → deny That would explain why the Administrator receives HTTP 200 while Shop Manager receives HTTP 403. Verification Inspect the permission callback for: role comparisons administrator checks hard-coded role names custom authorization conditions --- Hypothesis C — Custom capability was not assigned to Shop Manager Plausibility: Moderate The permission callback may intentionally require a custom capability, but the Shop Manager role may not have been granted it. Verification Compare: Required capability vs Shop Manager capabilities Also verify whether the capability assignment occurs during plugin activation or another initialization process. --- Hypothesis D — Security plugin is blocking the endpoint Plausibility: Weak to moderate A security plugin could potentially alter REST API access. However, the recent permission-callback modification provides stronger evidence for an application-level authorization problem. Verification Test the endpoint on staging with the relevant security layer isolated. --- 5. 📊 Evidence Assessment Hypothesis Assessment Evidence Incorrect capability check Strongly supported Role-specific 403 + recent permission change Administrator-only authorization logic Strongly supported Admin succeeds while Shop Manager fails Missing custom capability Plausible Depends on endpoint implementation Security plugin interference Possible No direct evidence yet JavaScript failure Weak Request reaches REST API and receives 403 No hypothesis should be called the confirmed root cause until the permission callback and capability requirements are inspected. --- 6. 🔎 Root-Cause Isolation Test 1 — Inspect the endpoint Locate the REST route registration and examine: register_rest_route() Specifically inspect: 'permission_callback' Determine exactly what condition returns true or false. --- Test 2 — Identify the required capability If the callback contains something conceptually like: current_user_can( 'some_capability' ) record that capability. Then determine whether Shop Manager possesses it. Do not simply change the capability yet. --- Test 3 — Compare authorization contexts Test the endpoint with: 👑 Administrator → expected 200 🛒 Shop Manager → currently 403 👤 Unauthorized user → expected 403 This confirms whether the authorization boundary is behaving according to the intended access model. --- Test 4 — Check the recent code change Compare the current permission callback with the previous implementation. Look specifically for changes involving: current_user_can() user roles custom capabilities is_user_logged_in() REST authentication permission callback conditions This is particularly valuable because the permission logic was recently modified. --- 7. 💻 Code Investigation Suppose the endpoint contains logic conceptually equivalent to: 'permission_callback' => function () { return current_user_can( 'manage_options' ); } The important question is not: > "How do we remove the 403?" The correct question is: > "Is manage_options actually the intended authorization requirement for this endpoint?" If the endpoint is supposed to be available to authorized Shop Managers, using an administrator-level capability would be an authorization design mismatch. The fix should therefore use the minimum capability appropriate for the intended data access, rather than simply allowing every authenticated user. --- 8. 🔐 Security Analysis This bug has an important security dimension. A careless fix such as: return is_user_logged_in(); could make sensitive customer statistics accessible to users who should not have access. Likewise, removing the permission_callback entirely would be inappropriate for a protected internal endpoint. The authorization model should answer: Who should access this data? ↓ What capability represents that permission? ↓ Does the endpoint enforce that capability? The fix must preserve the intended access boundary. --- 9. 🎯 Root-Cause Conclusion Current leading hypothesis The REST endpoint's recently modified permission callback is enforcing an authorization condition that Shop Manager users do not satisfy. The evidence supporting this is: Administrator receives HTTP 200. Shop Manager receives HTTP 403. The endpoint itself is functioning. The failure is role-specific. Permission logic was recently changed. There is no evidence of a JavaScript failure or PHP fatal error. Confirmed root cause Not yet confirmed. The exact permission_callback and required capability must be inspected before declaring the root cause confirmed. --- 10. 🛠️ Recommended Fix Strategy Once the callback is verified, use the intended authorization model. For example, if the business requirement is: Administrator → allowed Shop Manager → allowed Other users → denied then implement authorization around an appropriate capability shared by those intended roles, rather than blindly checking for Administrator status. The exact capability should be determined from the site's actual permission model. Avoid: removing authorization allowing every logged-in user hard-coding a temporary bypass modifying WordPress core weakening REST API security just to eliminate the 403 --- 11. 🧪 Regression Tests After the fix, test: 👑 Administrator → REST request → 200 → Valid statistics 🛒 Shop Manager → REST request → 200 → Valid statistics 👤 Unauthorized user → REST request → 401/403 according to authentication design → No protected statistics Also test: 📱 Mobile dashboard 💻 Desktop dashboard 🔄 Page refresh 🔐 Expired authentication/session 🚫 User without required capability The most important regression test is not simply "dashboard loads." It must verify that authorized users can access the data while unauthorized users remain blocked. --- 12. 🚀 Production Safety Before deployment: 1. Back up the plugin/code. 2. Apply the authorization change on staging. 3. Test Administrator access. 4. Test Shop Manager access. 5. Test an unauthorized account. 6. Verify that sensitive customer data is not exposed. 7. Deploy the smallest necessary code change. 8. Monitor REST API responses after deployment. No database migration should be necessary unless the investigation discovers that the custom capability itself is missing. --- 13. 🏁 Final Engineering Diagnosis Observed problem: Shop Manager receives HTTP 403 from a custom WordPress REST API endpoint. Expected: Authorized Shop Managers should receive customer statistics. Failure point: REST API authorization / permission_callback. Strongest hypothesis: The recently modified permission logic requires a capability or authorization condition that Shop Managers do not satisfy. Confirmed root cause: Not yet established without inspecting the actual callback. Best verification: Inspect register_rest_route() → permission_callback → required capability → Shop Manager capability set. Recommended fix: Correct the authorization rule to match the intended access model while preserving protection of customer data. Regression requirement: Test both sides of the security boundary — authorized Shop Managers must succeed, and unauthorized users must remain blocked. 🔐