Answers.Body: <p>I found <a href="https://github.com/craftcms/cms/issues/4927#issuecomment-575360828" rel="nofollow noreferrer">the fix here</a></p>
  <p><code>composer install --ignore-platform-reqs</code></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-02-13T01:04:51.117Z
Answers.LastActivityDate: 2021-02-13T01:04:51.117Z
Answers.UserDisplayName: doctorgloom
Body: <p>I'm new to Craft so maybe I'm doing something dumb, but I can't get past this error screen when trying to update to 3.6:</p>
  <pre><code>Composer output: Loading composer repositories with package information
  Updating dependencies
  Your requirements could not be resolved to an installable set of packages.
  
  Problem 1
  - Can only install one of: yiisoft/yii2[2.0.38, 2.0.40].
  - Can only install one of: yiisoft/yii2[2.0.40, 2.0.38].
  - craftcms/cms 3.6.5.1 requires yiisoft/yii2 ~2.0.40.0 -&gt; satisfiable by yiisoft/yii2[2.0.40].
  - Installation request for craftcms/cms 3.6.5.1 -&gt; satisfiable by craftcms/cms[3.6.5.1].
  - Installation request for yiisoft/yii2 (installed at 2.0.38) -&gt; satisfiable by yiisoft/yii2[2.0.38].
  
  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.
  </code></pre>
  <p>I deleted the composer.lock file based on some threads I found here, and I tried running <code>composer update</code> from the terminal and it did reduce a much longer error message down to this one, but still no joy.</p>
  <p>I'm developing locally on MAMP, 3.5.x was running great.</p>
  <p>My <code>composer.json</code>:</p>
  <pre><code>{
    &quot;require&quot;: {
      &quot;craftcms/cms&quot;: &quot;3.5.18&quot;,
      &quot;craftcms/contact-form&quot;: &quot;2.2.7&quot;,
      &quot;craftcms/feed-me&quot;: &quot;4.3.4&quot;,
      &quot;craftcms/mailgun&quot;: &quot;1.4.3&quot;,
      &quot;craftcms/redactor&quot;: &quot;2.8.5&quot;,
      &quot;vlucas/phpdotenv&quot;: &quot;^3.4.0&quot;
    },
    &quot;require-dev&quot;: {
      &quot;yiisoft/yii2-shell&quot;: &quot;^2.0.3&quot;
    },
    &quot;autoload&quot;: {
      &quot;psr-4&quot;: {
        &quot;modules\\&quot;: &quot;modules/&quot;
      }
    },
    &quot;config&quot;: {
      &quot;sort-packages&quot;: true,
      &quot;optimize-autoloader&quot;: true,
      &quot;platform&quot;: {
        &quot;php&quot;: &quot;7.2.5&quot;
      }
    },
    &quot;scripts&quot;: {
      &quot;post-root-package-install&quot;: [
        &quot;@php -r \&quot;file_exists('.env') || copy('.env.example', '.env');\&quot;&quot;
      ]
    }
  }
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-02-13T00:37:24.000Z
Comments.Text: If you put a ^ in front of all of the dependencies (i.e. `"craftcms/cms": "^3.5.18", "craftcms/contact-form": "^2.2.7",`, etc.) then run `composer update`, does that help?
Comments.UserDisplayName: Brad Bell
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-02-13T00:54:24.220Z
Comments.Text: Tried but now I'm getting the error: Install or enable PHP's zip extension. Quick search suggests it's not available on MAMP I guess, so maybe that's the problem?
Comments.UserDisplayName: doctorgloom
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-02-13T01:02:04.650Z
Comments.Text: Just found the fix: composer install --ignore-platform-reqs
Comments.UserDisplayName: doctorgloom
Tags: <updating>
Title: Craft 3.6 Upgrade errors - can only install one of yiisoft/yii2 (and other errors)
ThreadText: # Craft 3.6 Upgrade errors - can only install one of yiisoft/yii2 (and other errors)
  
  (Asked by: username_0 on 2021-02-12)
  
  I'm new to Craft so maybe I'm doing something dumb, but I can't get past this error screen when trying to update to 3.6:
  
  ```
  Composer output: Loading composer repositories with package information
  Updating dependencies
  Your requirements could not be resolved to an installable set of packages.
  
  Problem 1
  - Can only install one of: yiisoft/yii2[2.0.38, 2.0.40].
  - Can only install one of: yiisoft/yii2[2.0.40, 2.0.38].
  - craftcms/cms 3.6.5.1 requires yiisoft/yii2 ~2.0.40.0 -> satisfiable by yiisoft/yii2[2.0.40].
  - Installation request for craftcms/cms 3.6.5.1 -> satisfiable by craftcms/cms[3.6.5.1].
  - Installation request for yiisoft/yii2 (installed at 2.0.38) -> satisfiable by yiisoft/yii2[2.0.38].
  
  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.
  
  ```
  
  I deleted the composer.lock file based on some threads I found here, and I tried running `composer update` from the terminal and it did reduce a much longer error message down to this one, but still no joy.
  
  I'm developing locally on MAMP, 3.5.x was running great.
  
  My `composer.json`:
  
  ```
  {
    "require": {
      "craftcms/cms": "3.5.18",
      "craftcms/contact-form": "2.2.7",
      "craftcms/feed-me": "4.3.4",
      "craftcms/mailgun": "1.4.3",
      "craftcms/redactor": "2.8.5",
      "vlucas/phpdotenv": "^3.4.0"
    },
    "require-dev": {
      "yiisoft/yii2-shell": "^2.0.3"
    },
    "autoload": {
      "psr-4": {
        "modules\\": "modules/"
      }
    },
    "config": {
      "sort-packages": true,
      "optimize-autoloader": true,
      "platform": {
        "php": "7.2.5"
      }
    },
    "scripts": {
      "post-root-package-install": [
        "@php -r \"file_exists('.env') || copy('.env.example', '.env');\""
      ]
    }
  }
  
  ```
  
  **Tags:** updating
  
  > **Comments:**
  > **username_1**: If you put a ^ in front of all of the dependencies (i.e. `"craftcms/cms": "^3.5.18", "craftcms/contact-form": "^2.2.7",`, etc.) then run `composer update`, does that help?  
  > **username_0**: Tried but now I'm getting the error: Install or enable PHP's zip extension. Quick search suggests it's not available on MAMP I guess, so maybe that's the problem?  
  > **username_0**: Just found the fix: composer install --ignore-platform-reqs  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_0 on 2021-02-13. Score: 2
  
  I found [the fix here](https://github.com/craftcms/cms/issues/4927#issuecomment-575360828)
  
  `composer install --ignore-platform-reqs`
  
  
  ---
  
  