Answers.Body: <p>I think what ended up working was restoring backed up composer.json and composer.lock files, deleting everything in /vendor directory, and then running <code>composer install</code></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-01-17T23:29:12.847Z
Answers.Text: I ran into this issue while taking over a project. My issue was my DB had updated plugins that my `composer.json` file didn't have. Removing the `vendor` folder and the `composer.` files, then adding the correct `composer.json` file that matched the updated DB worked as well.
Answers.UserDisplayName: Jeff Irwin
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-07-15T00:54:46.063Z
Answers.LastActivityDate: 2019-07-15T00:54:46.063Z
Answers.UserDisplayName: Roger Glenn
Body: <p>Steps to reproduce:</p>
  
  <ol>
  <li>Log into control panel,</li>
  <li>Go to Plugin Store tab and install a plugin (in my case hillholliday/craft-user-manual or dolphiq/sitemap),</li>
  <li>Plugin installation error screen,</li>
  <li>Navigate to /admin and entire site errors out with this message (control panel and frontend)</li>
  </ol>
  
  <p><code>unserialize(): Error at offset 0 in ProjectConfig.php</code></p>
  
  <p><a href="https://i.sstatic.net/b22Ex.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/b22Ex.png" alt="enter image description here"></a></p>
  
  <p>Unsuccessful attempts to correct the issue include:</p>
  
  <ol>
  <li><p>Restoring latest database backup</p></li>
  <li><p>Restoring backed up composer.json and composer.lock files from storage/composer-backups and running <code>composer install</code></p></li>
  <li><p>Clearing <code>storage/runtime/cache</code></p></li>
  </ol>
  
  <p>Any suggestions on how to resolve this issue, and insights to why it's happening in the first place?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2019-07-14T20:07:25.397Z
Comments.Text: Have you already tried to install the plugins via composer? I have reproduced the steps and I don't get the error.
Comments.UserDisplayName: Fred
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2019-07-15T00:53:59.367Z
Comments.Text: Thanks for replying! Yes, I tried uninstalling and re-installing the plugins via composer and that didn't work either. I eventually got my site back up and running after scrambling and trying a bunch of different things. I think what ended up working was restoring backed up composer.json and composer.lock files, deleting everything in /vendor directory, and then running composer install.
Comments.UserDisplayName: Roger Glenn
Tags: <plugins>
Title: unserialize(): Error at offset 0 after attempting to download and install plugin within control panel
ThreadText: # unserialize(): Error at offset 0 after attempting to download and install plugin within control panel
  
  (Asked by: username_0 on 2019-07-14)
  
  Steps to reproduce:
  
  1. Log into control panel,
  2. Go to Plugin Store tab and install a plugin (in my case hillholliday/craft-user-manual or dolphiq/sitemap),
  3. Plugin installation error screen,
  4. Navigate to /admin and entire site errors out with this message (control panel and frontend)
  
  `unserialize(): Error at offset 0 in ProjectConfig.php`
  
  [![enter image description here](https://i.sstatic.net/b22Ex.png)](https://i.sstatic.net/b22Ex.png)
  
  Unsuccessful attempts to correct the issue include:
  
  1. Restoring latest database backup
  2. Restoring backed up composer.json and composer.lock files from storage/composer-backups and running `composer install`
  3. Clearing `storage/runtime/cache`
  
  Any suggestions on how to resolve this issue, and insights to why it's happening in the first place?
  
  **Tags:** plugins
  
  > **Comments:**
  > **username_1**: Have you already tried to install the plugins via composer? I have reproduced the steps and I don't get the error.  
  > **username_0**: Thanks for replying! Yes, I tried uninstalling and re-installing the plugins via composer and that didn't work either. I eventually got my site back up and running after scrambling and trying a bunch of different things. I think what ended up working was restoring backed up composer.json and composer.lock files, deleting everything in /vendor directory, and then running composer install.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_0 on 2019-07-15. Score: 2
  
  I think what ended up working was restoring backed up composer.json and composer.lock files, deleting everything in /vendor directory, and then running `composer install`
  
  > **Comments:**
  > **username_2**: I ran into this issue while taking over a project. My issue was my DB had updated plugins that my `composer.json` file didn't have. Removing the `vendor` folder and the `composer.` files, then adding the correct `composer.json` file that matched the updated DB worked as well.  
  
  ---
  
  