- Phones and tablets
- Android phones and tablets
Certificate not trusted
Google Certificate not trusted in Gmail Android: IMAP SSL error
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
The Certificate not trusted error in the Gmail app for Android happens when manually adding another email account whose SSL/TLS certificate is invalid; try automatic setup or verify the IMAP server and port 993. If it persists, tap More info and share the report with your email provider.
Safety first
Stop and check this first
- If you see the Email security not guaranteed message during manual setup or select None under Security type, your connection is not encrypted and someone could potentially intercept your username, password, or message information.
Safe checks you can perform
- Try automatic account setup first if your email provider is listed in Gmail
- Verify the incoming IMAP server, port 993, SSL/TLS security type, and app password settings
- Export and share the certificate error details using the More info link
Leave these tasks to a qualified professional
- Do not attempt this professional task: Report the certificate error to your other email service provider
- Do not attempt this professional task: Confirm incoming IMAP hostname and SSL/TLS certificate chain with the mail server administrator
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Report the certificate error to your other email service provider
What they doShare the certificate details captured via More info > More > Share with your other email provider's support team so they can inspect and fix their mail server certificate.
They must show youthe More info screen in the Gmail app showing the exact SSL/TLS certificate mismatch or expiration reason.
In writingthe exported certificate report from the Gmail app and the support ticket number from your email provider.
Confirm incoming IMAP hostname and SSL/TLS certificate chain with the mail server administrator
What they doIf you are adding a custom-domain or workplace account via Personal (IMAP), ask your domain or mail administrator to verify the SSL/TLS certificate subject, hostname, and validity on port 993.
They must show youthe Incoming server settings screen in the Gmail Android app showing the IMAP server, port 993, and SSL/TLS security type.
In writingthe verified incoming and outgoing server hostnames for your domain and confirmation of the server's SSL/TLS certificate renewal.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Try automatic account setup first if your email provider is listed in Gmail
- Who:
- User adding a non-Gmail email address in the Gmail app on Android.
- How:
- Open the Gmail app, tap your profile icon in the top right, and tap Add another account. If your email service (such as Outlook, iCloud Mail, or Yahoo) is listed on the Set up email screen, select it and follow the automatic prompts instead of tapping Other.
- Result that matters:
- Whether your email provider connects through the automatic setup flow without a certificate error.
- If your provider appears in the list and finishes automatic setup:
- your account is connected securely.
- If your email service is not listed and requires Other > Personal (IMAP):
- check the exact server settings next.
- Evidence to keep:
- Screenshot of the Set up email provider list in the Gmail app on Android.
Evidence: Gmail Help - Fix problems adding an account to the Gmail app (Certificate not trusted)
Verify the incoming IMAP server, port 993, SSL/TLS security type, and app password settings
- Who:
- Account holder entering manual IMAP settings in the Gmail app.
- How:
- Check your email provider's help section to confirm the exact incoming IMAP server hostname (for example, imap.mail.com), port 993, and Security type SSL/TLS. If your account uses extra security measures like 2-Step Verification, sign in using an alternative method such as an app password.
- Result that matters:
- Whether the entered IMAP hostname and port match the secure mail server documented by your provider.
- If correcting the IMAP hostname or using an app password succeeds:
- complete the remaining setup prompts.
- If the certificate error still appears with the official server settings:
- export the certificate details using More info.
- Evidence to keep:
- Screenshot of the Incoming server settings screen (IMAP server, port, and security type) in Gmail.
Evidence: Gmail Help - Fix problems adding an account to the Gmail app (Certificate not trusted)
Export and share the certificate error details using the More info link
- Who:
- User seeing the certificate warning during manual setup in the Gmail app.
- How:
- In the certificate error message inside the Gmail app, tap More info. In the top right corner of that screen, tap More (three dots) and select Share to save or send the certificate details to your other email service.
- Result that matters:
- Exported SSL/TLS certificate report ready to send to your email provider's support team.
- If you export the details via Share:
- send the report to your email provider so they can fix their certificate.
- If you see the Email security not guaranteed prompt:
- do not select Security type None; wait for your provider to fix SSL/TLS.
- Evidence to keep:
- Exported text or screenshot from More info > More > Share in the Gmail app.
Evidence: Gmail Help - Fix problems adding an account to the Gmail app (Certificate not trusted)
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Phones and tablets
- Brand
- Product type
- Android phones and tablets
Known code variants
- Certificate expired or not yet valid Gmail Android
- Certificate not found Gmail manual IMAP setup
- Certificate not trusted when adding account to Gmail app
- Certificate subject and hostname mismatch Gmail app
- El asunto y el nombre de host del certificado no coinciden Gmail
- El certificado ha caducado o aun no es valido Gmail Android
- El certificado no es de confianza Gmail Android
- error El certificado no es de confianza al anadir cuenta en Gmail
- Google Certificate not trusted Gmail Android
What it means
According to Gmail Help's official guide for fixing problems adding an account to the Gmail app (article 6078445), the message Certificate not trusted and related alerts (Certificate expired or not yet valid, Certificate has been changed, Certificate subject and hostname mismatch, or Certificate not found) appear during manual account setup when your other email service does not use a valid, secure certificate. Menu labels may vary across Android versions, and this error alone never proves that your phone or the Gmail app is defective.
Warnings and stop conditions
- Higheditorial warning
If you see the Email security not guaranteed message during manual setup or select None under Security type, your connection is not encrypted and someone could potentially intercept your username, password, or message information.
Evidence: Gmail Help - Fix problems adding an account to the Gmail app (Certificate not trusted)
Symptoms and causes
Probable causes · in order
- External email provider's SSL/TLS certificate is untrusted, expired, or modifiedCommon
The mail server for the non-Gmail account you are adding presents a security certificate that is not trusted, has expired or is not yet valid, has been changed, or cannot be found.
Evidence: Gmail Help - Fix problems adding an account to the Gmail app (Certificate not trusted)
- Incorrect incoming IMAP server hostname or port entered during manual setupPossible
When setting up the account under Other > Personal (IMAP), the entered IMAP server hostname does not match the certificate subject or does not use port 993 with SSL/TLS security.
Evidence: Gmail Help - Fix problems adding an account to the Gmail app (Certificate not trusted)
- Account uses extra security such as 2-Step Verification requiring an app passwordLess common
Your external email provider enforces additional sign-in protections like 2-Step Verification and rejects standard manual authentication until you use an alternative method such as an app password.
Evidence: Gmail Help - Fix problems adding an account to the Gmail app (Certificate not trusted)
Virtual technician
Does Certificate not trusted still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Gmail Help - Fix problems adding an account to the Gmail app (Certificate not trusted)
Google · 2026 · official_doc
- 2
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