Problem: Got the below error when running mysql_upgrade
Incorrect database name '#mysql50#.rocksdb' when selecting the database

Solution:
systemctl stop mariadb
cp -R /var/lib/mysql /var/lib/mysql.bak
rm -rf /var/lib/mysql/.rocksdb/
systemctl start mariadb

Reference:
https://www.suse.com/support/kb/doc/?id=7014519

Problem:
[proxy_fcgi:error] [pid 3659] (70007)The timeout specified has expired: [client :39524] AH01075: Error dispatching request to : (polling)

Solution:
vim /etc/httpd/conf/httpd.conf
Timeout 600

systemctl reload httpd

Reference: https://stackoverflow.com/questions/46594731/php-apache-error-dispatching-request

The following previous generation instance types support PV AMIs: C1, C3, HS1, M1, M3, M2, and T1. Current generation instance types do not support PV AMIs.

Reference: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/virtualization_types.html

Disable email notification from cron job

crontab -e

Add the below line to the top.
MAILTO=""

Steps to resolve:
1. npm install
2. cd node_modules/react-native
3. scripts/ios-install-third-party.sh
4. cd third-party/glog-0.3.5
5. ./configure
6. cd ../../../../
7. react-native run-ios

** DO NOT execute "react-native run-ios" until step 7.

Reference: https://github.com/facebook/react-native/issues/19774#issuecomment-427213573

card-img distorted in IE 11

Solution:
Add min-height: 0.1px to .card-img

Set Password Expiry Date for an user

chage -M number-of-days username

Handle error of file_get_contents()

$content = @file_get_contents(...)
if ($content === false) {
    ...
}

Step 1. Download http://curl.haxx.se/ca/cacert.pem and save it to /Applications/AMPPS/extra/etc/openssl/certs/cacert.pem

Step 2. Add the below lines into php.ini

[curl]
curl.cainfo="/Applications/AMPPS/extra/etc/openssl/certs/cacert.pem"
openssl.cafile="/Applications/AMPPS/extra/etc/openssl/certs/cacert.pem"

Solution 1
1. Use verbose mode to see the error

ssh -v xxx.xxx.xxx.xxx

2. Delete the corresponding row in ~/.ssh/known_hosts

Reference: https://stackoverflow.com/questions/18551556/permission-denied-publickey-when-ssh-access-to-amazon-ec2-instance

Solution 2
1. Detach the volume
2. Create a temporary ec2 instance and attach the volume into it
3. Login to the temporary ec2 instance
4. Check the device code

lsblk

5. Mount the volume (/dev/xvdg)

mkdir mount_point
mount /dev/xvdg1 mount_point

6. Change the ssh config.
7. Attach the volume back to the original ec2 instance
8. Delete the temporary ec2 instance
9. Delete the corresponding row in ~/.ssh/known_hosts and try again

Reference:
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/TroubleshootingInstancesConnecting.html#TroubleshootingInstancesConnectingMindTerm

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