How to Fix ERR_CERT_CONTAINS_ERRORS in Chrome (Pakistan Guide)

When navigating to an enterprise portal, internal dashboard, or newly provisioned web application in Pakistan, Google Chrome or Chromium-based browsers may abruptly display a red interstitial warning:

Your connection is not private
Attackers might be trying to steal your information from portal.domain.pk...
NET::ERR_CERT_CONTAINS_ERRORS

Unlike ordinary certificate expiration or domain mismatch warnings that provide an “Advanced -> Proceed to site” bypass link, ERR_CERT_CONTAINS_ERRORS is treated by Chromium’s BoringSSL crypto engine as a fatal transport violation. The browser completely blocks navigation.

In this technical guide, we dissect the underlying ASN.1 syntax violations, inspect binary certificate structures using OpenSSL, and demonstrate how to re-issue clean, RFC-compliant certificates.

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1. What Triggers ERR_CERT_CONTAINS_ERRORS?

Chromium relies on Google’s BoringSSL library for TLS negotiation. While older cryptographic libraries were lenient when parsing malformed X.509 certificates, modern BoringSSL enforces strict Distinguished Encoding Rules (DER) defined in ITU-T X.690 and RFC 5280.

If any field inside the certificate violates DER grammar, the parser aborts before evaluating trust or expiration:

Common ASN.1 Malformations in Pakistani Deployments

Syntax Malformation	Technical Cause	BoringSSL / Chrome Verdict
Negative Serial Number	Most Significant Bit (MSB) of serial is 1 without leading 0x00 padding	Fatal syntax error
Trailing Null/Garbage in SAN	Bash scripts appending newline \n or null \0 bytes into DNS names	Parse failure in SubjectAltName
BER vs DER Length Encodings	Indefinite length encoding used instead of definite DER octets	Strict DER parsing violation
Non-Printable Characters	PrintableString encoding used with characters outside ASCII alphanumeric	Type-constraint violation
Invalid UTCTime / GeneralizedTime	Omitting the trailing Z UTC zone indicator or malformed second offsets	Date-time validation fault

In Pakistan, this error frequently surfaces when webmasters generate self-signed certificates using automated shell scripts with unescaped variables or when legacy hardware load balancers issue non-standard certificates.

For mission-critical production environments requiring high availability and hardware crypto offloading, bare-metal isolation is critical. Discover our enterprise Dedicated Servers and localized Dedicated Servers in Pakistan deployed in Tier-3 Karachi facilities.

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2. Inspecting ASN.1 Structure via OpenSSL CLI

Standard openssl x509 -text commands often swallow or normalize parsing errors. To detect true DER malformations, use OpenSSL’s low-level ASN.1 parser:

# Fetch and inspect raw ASN.1 DER structure from the remote host
openssl s_client -connect portal.domain.pk:443 -servername portal.domain.pk </dev/null 2>/dev/null | openssl x509 -outform DER | openssl asn1parse -inform DER -dump

Checking for Negative Serial Numbers

Run this targeted command to inspect the serial number’s hexadecimal representation:

openssl s_client -connect portal.domain.pk:443 -servername portal.domain.pk </dev/null 2>/dev/null | openssl x509 -noout -serial

If the serial number begins with a byte value between 80 and FF in hexadecimal and lacks a leading 00 octet, BoringSSL interprets the integer in two’s complement notation as a negative number, which RFC 5280 explicitly prohibits:

RFC 5280 Section 4.1.2.2:
"Certificate users MUST be able to handle serialNumber values up to 20 octets.
Conforming CAs MUST NOT use serialNumber values longer than 20 octets.
Note: Non-conforming CAs may issue certificates with serial numbers that are negative."

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3. Resolving SAN Syntax and Encoding Violations

The most frequent culprit behind ERR_CERT_CONTAINS_ERRORS is a malformed Subject Alternative Name (SAN) extension caused by shell formatting errors.

The Broken Pattern:

# BROKEN: Unescaped trailing characters or empty entries
subjectAltName = DNS:portal.domain.pk, DNS:  # Empty entry causes ASN.1 parse failure!

The Clean, RFC 5280-Compliant Config (cert_clean.cnf)

[ req ]
default_bits        = 2048
distinguished_name  = req_distinguished_name
req_extensions      = req_ext
prompt              = no

[ req_distinguished_name ]
C                   = PK
ST                  = Sindh
L                   = Karachi
O                   = Enterprise Systems PK
CN                  = portal.domain.pk

[ req_ext ]
keyUsage            = critical, digitalSignature, keyEncipherment
extendedKeyUsage    = serverAuth
subjectAltName      = @alt_names

[ alt_names ]
DNS.1               = portal.domain.pk
DNS.2               = www.portal.domain.pk
IP.1                = 103.151.44.15

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4. Re-issuing Clean Certificates via OpenSSL

Generate the new private key and sign the certificate with explicit DER compliance:

# 1. Generate 2048-bit RSA private key
openssl genrsa -out /etc/ssl/private/portal_clean.key 2048
chmod 0600 /etc/ssl/private/portal_clean.key

# 2. Generate Certificate Signing Request
openssl req -new -key /etc/ssl/private/portal_clean.key \
    -config cert_clean.cnf \
    -out /etc/ssl/certs/portal_clean.csr

# 3. Self-sign with explicit positive serial number generation
openssl x509 -req -days 365 \
    -in /etc/ssl/certs/portal_clean.csr \
    -signkey /etc/ssl/private/portal_clean.key \
    -extfile cert_clean.cnf \
    -extensions req_ext \
    -sha256 \
    -set_serial $(openssl rand -hex 16 | sed 's/^[89abcdef]/0&/') \
    -out /etc/ssl/certs/portal_clean.crt

Notice the -set_serial flag: it guarantees that if the first hexadecimal character is 8 through f, a leading zero (0) is prefixed, mathematically preventing negative serial numbers.

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5. Automated Re-issuance via Certbot (Production Standard)

If the server is publicly reachable across Pakistan, standardizing on automated ACME certificate management via Let’s Encrypt guarantees DER compliance:

# Obtain cleanly formed ECDSA certificate
certbot certonly --standalone -d portal.domain.pk --key-type ecdsa --register-unsafely-without-email

Update your web server configuration:

# Nginx TLS Configuration
server {
    listen 443 ssl http2;
    server_name portal.domain.pk;

    ssl_certificate /etc/letsencrypt/live/portal.domain.pk/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/portal.domain.pk/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers HIGH:!aNULL:!MD5;
}

Reload Nginx:

nginx -t && systemctl reload nginx

Upon reloading Google Chrome, the NET::ERR_CERT_CONTAINS_ERRORS exception will disappear, establishing a secure TLS 1.3 session with a valid padlock.

For related browser certificate issues and cryptographic validation, consult our tutorials on How to fix SEC_ERROR_INADEQUATE_KEY_USAGE in Firefox and How to fix SEC_ERROR_CERT_SIGNATURE_ALGORITHM_DISABLED in Firefox. If you run complex multi-site environments, review our performant Cloud VPS offerings.

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