Job auth-session-drops-after-login-cookie · revised 11 October 2026
Fix users being logged out straight after a successful login
After login, a test user stays signed in across page loads in the agreed environments, and across a browser restart where a lasting session is agreed. The cookie is set, sent back and kept.
You might be seeing
- The login form accepts the password and then shows the login page again with no error
- Users are signed in on one page and signed out on the next, or after a few seconds
- It works in one browser or on the default hosting address but not on the live domain
No passwords, keys, card details or admin invites needed to start.
What usually happened
The server believes it signed the user in, but the browser does not keep the session cookie or does not send it back on the next request. Typical causes are cookie attributes that the browser rejects or scopes away (Secure, SameSite, Domain, Path), a proxy that makes the app believe the connection is plain HTTP, or a session store that differs between servers. The job finds the one cause by tracing a single test login and repairs the app-side setting.
Who it’s for: A founder or product owner whose web app accepts the login but then sends users back to the login page, or signs them out within seconds, usually in production or on a custom domain rather than on a developer machine.
Usually starts when: Login worked locally or on a default hosting address and loops or drops after a move to a custom domain, a reverse proxy or load balancer, an added subdomain, a change of hosting, or a change to cookie settings.
The result: In each agreed environment a test user logs in, stays signed in across at least ten page loads and, where a lasting session with an expiry is agreed in writing, a full browser restart within the agreed session lifetime, and is signed out when they log out. You receive the cause in plain words, the change, and redacted evidence of the cookie behaviour before and after.
Check whether this job fits
These questions and one browser check tell you whether a cookie fault is likely. They do not need credentials, cookie values or source code.
Checks you can run yourself
Watch the login response in the browser
Open the browser developer tools on the Network tab, log in once with a test account, select the response that redirects you after login and open the Cookies view. Do not copy the cookie value.
Look for: Whether a cookie is set at all, and its Secure, SameSite, Domain and Path settings. A rejected cookie is usually flagged with a warning beside it. Note whether the next request carries it.
What you get
- A pull request with the change and a note naming the cause
- Redacted before and after traces of the login response and the following request, with the cookie value removed
- Written steps for any proxy, host or domain setting that only your hosting contact can change
- Reversal steps and any limits found
Included
- One web app and one login method, in up to two agreed environments, for the agreed browsers
- Trace a single test login, recording the response that sets the session cookie and the next request that should carry it
- Identify which attribute, scope or server setting stops the cookie being kept or returned
- Repair the app-side cookie and session settings, including trusting the forwarded protocol of your own proxy where that is the cause
- Give your hosting contact the exact proxy or host setting to change, when the cause is outside the app
- Re-test with a test account and record redacted evidence
Not included
- Changing sign-in provider or building a new login system
- Third-party social sign-in errors at the provider: see the callback repair outcome
- Security review, penetration testing or session-hijacking investigation
- Single sign-on across several of your products, or cookie sharing between different registrable domains
- Production deployment, host or DNS changes, which stay with your team
- Users logged out by a deliberate short session lifetime that you chose
How we know it’s done
Agreed with you before work starts. Each check produces evidence you keep.
In each agreed environment a test user logs in and stays signed in across ten consecutive page loads of agreed signed-in pages, without being returned to the login page.
Evidence: A redacted request log or recording for each environment showing the cookie sent on every one of the ten requests.
After logout the next request is treated as signed out. Where a lasting session with an expiry was agreed in writing before work, closing and reopening the browser within the agreed session lifetime also leaves the same test user signed in; where only a session cookie (removed when the browser closes) was agreed, the restart check is not run.
Evidence: Dated before and after results for logout in each agreed browser, and for the restart where it was agreed.
The response that sets the session cookie shows the agreed attributes (HttpOnly, Secure on HTTPS, an explicit SameSite value and the narrowest Domain and Path that work), with the value removed.
Evidence: A redacted copy of the cookie header and the agreed attribute list side by side.
The diff contains no secret or cookie value, and the existing login tests, or an agreed manual check, still pass.
Evidence: The changed-file list, a secret scan of the diff and the test results.
Sign-off. You or your authorised maintainer review the evidence, run one test login on the live address after your team deploys, sign off in writing and merge. Payment follows sign-off.
If it fails. If the agreed test login does not stay signed in in an agreed environment, you do not pay for this fixed scope. If the cause is outside the app, such as a cookie blocker or a host setting nobody can change, we explain what we found and stop. Wider work needs a new written agreement.
When it fits, and when we stop
It fits when
- You can describe one login journey that fails and name the address where it fails
- The app can run in a copy or staging environment that uses the same proxy or host setup, with a test account and no customer data
- The login works at least once, meaning the server accepts the credentials
- You hold, or can reach whoever holds, the proxy and hosting settings
- An authorised maintainer on your side reviews and merges the change
We stop and tell you if
- The login itself fails (wrong password errors or a failed identity service), which is a different fault
- The failure appears only with real customer accounts or needs production credentials to reproduce
- The cause is a third-party cookie blocker or corporate browser policy that you cannot change
- Fixing it would need a redesign of how several products share one login
What could go wrong
Before merge, closing the pull request leaves the app unchanged. After merge, your maintainer can revert the commit and users simply log in again. Any proxy or host change we recommend is applied by your team and can be undone in the same place.
Scroll the table sideways to read it all.
| Risk | How we handle it |
|---|---|
| Loosening cookie attributes to make login work can weaken protection against theft or cross-site requests. | We change only the attribute proven to cause the failure, keep HttpOnly and Secure on where the site uses HTTPS, and the reviewer checks the final settings against the agreed list. |
| Trusting forwarded headers lets a client pretend to be on HTTPS or another host. | We trust forwarded values only from your own proxy, as documented by your framework, and note that the proxy must overwrite them. |
| The fix works on the test copy but not behind the real proxy. | The copy uses the same proxy path where possible, and acceptance includes a test login on the live address by your team after deployment. |
An independent reviewer checks that the session cookie is still protected, that the cause was reproduced and not guessed, and that no cookie value or secret appears in evidence. Your maintainer reviews and merges.
What you can check
This is a new service. We have not delivered this job for a client yet.
Other ways to get this done
- Your developer can inspect the cookie attributes the browser accepts. MDN explains Secure, SameSite, Domain and Path in plain terms. developer.mozilla.org
- OWASP lists recommended session cookie settings, which is a good checklist before changing any attribute. cheatsheetseries.owasp.org
Questions
Will you just turn off Secure or SameSite so it works?
No. We change only the attribute that is proven to cause the failure and keep the cookie as protected as the journey allows.
What if it only fails for some users?
Tell us which browsers or networks. A cause tied to one browser or a corporate policy may be outside this job, and we say so after a bounded look.
Do you need production access?
No. We use a copy and a test account. Your team does the final check on the live address.
Is this the same as a Google or GitHub login error?
No. A provider error appears before the user reaches your app. This job starts after the app accepts the login.
Send an enquiry
Send us
- The address where it fails, the address where it works, and which browsers show it
- Whether the app sits behind a proxy, load balancer or content network, and which hosting service is used
- What the user sees after a successful login, in one sentence
- Do not send passwords, session cookie values, source code, an access invitation or customer data in the first enquiry
Later, once you agree
- The source through an agreed company-controlled route, with a branch for the pull request
- A copy or staging environment with a test account, using the same proxy path as production where possible
- Read access to the proxy or host configuration you are willing to share, with secrets removed
- The name of the person who reviews and merges
You own the app, the domain, the proxy and the hosting. We work on a branch or copy through a company-controlled identity, never a personal login, using a test account. Session secrets stay with you and never appear in evidence. Your team applies proxy and host changes and deploys.
Email fallback: open your mail app
If website submission is unavailable, review and send the fallback email yourself. An email fallback is not a website receipt. Or write to hello@syntheticindustry.ai with “auth-session-drops-after-login-cookie” as the subject.