How To Fix "Error: Composer was unable to install the updates."

Question

I've been running an installation Craft CMS 3.0.0-RC13 for some time with no problems. However, now I cannot install new plugins nor can I remove any that are currently installed. I keep getting the same (or similar) error. The full response is included below.

I've tried

composer remove [package]

composer clear-cache

composer update 

Almost seems like Composer has been corrupted or something. I'm assuming that the information about "php version does not satisfy..." is related to the bad package because I didn't alter anything about my php configuration.

Composer was unable to install the updates.

Error: An error occurred

Output: Loading composer repositories with package information Updating dependencies Your requirements could not be resolved to an installable set of packages.

Problem 1 - The requested package am-impact/amnav could not be found in any version, there may be a typo in the package name. Problem 2 - symfony/intl v3.3.7 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.8 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.9 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.4.0 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.10 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.11 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.12 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.13 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.14 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.4.1 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.4.2 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.4.3 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.15 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.4.4 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.3.16 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - symfony/intl v3.4.5 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement. - Installation request for roave/security-advisories dev-master#3df94834c80037130b533703df4672785b6ea112 -> satisfiable by roave/security-advisories[dev-master]. - newism/craft3-fields 0.0.10 requires symfony/intl ^3.3 -> satisfiable by symfony/intl[v3.4.5, v3.3.16, v3.4.4, v3.3.15, v3.4.3, v3.4.2, v3.4.1, v3.3.14, v3.3.13, v3.3.12, v3.3.11, v3.3.10, v3.4.0, v3.3.9, v3.3.8, v3.3.7, v3.3.6, v3.3.5, v3.3.4, v3.3.3, v3.3.2, v3.3.1, v3.3.0]. - symfony/intl v3.3.6 conflicts with roave/security-advisories[dev-master]. - symfony/intl v3.3.5 conflicts with roave/security-advisories[dev-master]. - symfony/intl v3.3.4 conflicts with roave/security-advisories[dev-master]. - symfony/intl v3.3.3 conflicts with roave/security-advisories[dev-master]. - symfony/intl v3.3.2 conflicts with roave/security-advisories[dev-master]. - symfony/intl v3.3.1 conflicts with roave/security-advisories[dev-master]. - symfony/intl v3.3.0 conflicts with roave/security-advisories[dev-master]. - Installation request for newism/craft3-fields ^0.0.10 -> satisfiable by newism/craft3-fields[0.0.10].

Potential causes: - A typo in the package name - The package is not available in a stable-enough version according to your minimum-stability setting see for more details. - It's a private package and you forgot to add a custom repository to find it

Read for further common problems. Running update with --no-dev does not mean require-dev is ignored, it just means the packages will not be installed. If dev requirements are blocking the update you have to resolve those problems.

Answer 1

Problem 1 - The requested package am-impact/amnav could not be found in any version, there may be a typo in the package name.

am-impact/amnav isn't a valid Craft 3 plugin, so you need to move that reference from yourcomposer.json` file. You can see the full list of Craft 3 plugins here: https://plugins.craftcms.com/

symfony/intl v3.3.7 requires php ^5.5.9|>=7.0.8 -> your PHP version (7.0.27-1~dotdeb+8.1)...

All of those usually happen when you run a composer update/install on environment A that has higher library versions than environment B and you deploy the composer.lock file to environment B and try to run composer update again.

You can force Composer to use a "lowest common denominator" across all environments like so: https://github.com/pixelandtonic/craftcom/blob/develop/composer.json#L31-L33

Installation request for roave/security-advisories dev-master#3df94834c80037130b533703df4672785b6ea112 -> satisfiable by roave/security-advisories[dev-master]. - newism/craft3-fields 0.0.10 requires symfony/intl ^3.3

You can either remove roave/security-advisories from your composer.json file, remove newism/craft3-fields from it or wait for the author of the craft3-fields plugin to bump their symfony dependencies to a higher version that doesn't trigger roave/security-advisories.

Note that after making changes to your composer.json, you'll need to run composer update from terminal from your project's root.