Answers.Body: <p>Thanks to KarinG for giving me the right way to attack this question. </p>
  
  <p>The CiviCRM log had no record of the error. However, the error_log did. It read: </p>
  
  <p><code>[01-Sep-2016 10:17:39 America/Denver] PHP Fatal error: Cannot use object of type CRM_Contribute_Form_Task_PDFLetter as array in /home/mydomain/public_html/mysubdomain/sites/all/modules/civ‌​icrm/CRM/Contact/For‌​m/Task/PDFLetterComm‌​on.php on line 267</code></p>
  
  <p>Googling that error led me to <a href="https://issues.civicrm.org/jira/browse/CRM-19182" rel="nofollow">https://issues.civicrm.org/jira/browse/CRM-19182</a> which is reporting the problem as a bug in 4.7.10 that will be resolved in version 4.7.11. If, like me, you can't wait. Look at the commits linked from that page, or like KarinG said you can get the release candidate.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-09-01T16:44:32.930Z
Answers.LastActivityDate: 2016-09-01T16:44:32.930Z
Answers.UserDisplayName: Eric H
Answers.Body: <p>General recipe for Errors like that is to find a clue as to what's going on in the log files: first two places to check:</p>
  
  <ul>
  <li>check the CiviCRM log in /files/civicrm/ConfigAndLog/</li>
  <li>check your php and/or php-fpm error log (location of that depends on your install one possible option is: /var/log/httpd/</li>
  </ul>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-09-01T16:36:48.820Z
Answers.Text: You can try the rc - release candidate right now: http://dist.civicrm.org/by-date/2016-08-30/4.7.11-rc/
Answers.UserDisplayName: KarinG - Semper IT
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-09-01T16:43:15.697Z
Answers.Text: Sorry. Deleted my comment to post it as the answer. I edited the files listed in the github page's commits and I'm all fixed.
Answers.UserDisplayName: Eric H
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-08-27T15:30:28.370Z
Answers.LastActivityDate: 2016-08-27T15:30:28.370Z
Answers.UserDisplayName: KarinG - Semper IT
Body: <p>I'm getting an Error 500 result when trying to produce Thank You letters for contributions since upgrading to 4.7.10 (and Drupal 7.50). Other Print/Merge operations are functioning normally. Backtrace and debug do not produce any additional information. The error comes ~1 second after clicking "Make Thank-You Letters"--seeming as though it's not even processing the information.</p>
  
  <p>I've eliminated the following variables as the cause: Number of records, which records are selected, document type, thank you document body, page format, grouping.</p>
  
  <p>I read that Error 500 is often a permission error. Everything seems correct, but I'm no expert in that realm. Tried the sandbox demo and it's not a bug there.</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2016-08-26T21:19:33.233Z
Comments.Text: I think since it can't be reproduced on sandbox you'll need to dig in more and get some debug info.
Comments.UserDisplayName: Coleman
Tags: <contributions><error>
Title: Error 500 on Print/Merge Document page when doing Thank-Yous
ThreadText: # Error 500 on Print/Merge Document page when doing Thank-Yous
  
  (Asked by: username_0 on 2016-08-26)
  
  I'm getting an Error 500 result when trying to produce Thank You letters for contributions since upgrading to 4.7.10 (and Drupal 7.50). Other Print/Merge operations are functioning normally. Backtrace and debug do not produce any additional information. The error comes ~1 second after clicking "Make Thank-You Letters"--seeming as though it's not even processing the information.
  
  I've eliminated the following variables as the cause: Number of records, which records are selected, document type, thank you document body, page format, grouping.
  
  I read that Error 500 is often a permission error. Everything seems correct, but I'm no expert in that realm. Tried the sandbox demo and it's not a bug there.
  
  **Tags:** contributions, error
  
  > **Comments:**
  > **username_1**: I think since it can't be reproduced on sandbox you'll need to dig in more and get some debug info.  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_0 on 2016-09-01. Score: 2 | Accepted answer
  
  Thanks to KarinG for giving me the right way to attack this question.
  
  The CiviCRM log had no record of the error. However, the error\_log did. It read:
  
  `[01-Sep-2016 10:17:39 America/Denver] PHP Fatal error: Cannot use object of type CRM_Contribute_Form_Task_PDFLetter as array in /home/mydomain/public_html/mysubdomain/sites/all/modules/civ‌​icrm/CRM/Contact/For‌​m/Task/PDFLetterComm‌​on.php on line 267`
  
  Googling that error led me to <https://issues.civicrm.org/jira/browse/CRM-19182> which is reporting the problem as a bug in 4.7.10 that will be resolved in version 4.7.11. If, like me, you can't wait. Look at the commits linked from that page, or like KarinG said you can get the release candidate.
  
  
  ---
  
  ### Answer by username_2 on 2016-08-27. Score: 2
  
  General recipe for Errors like that is to find a clue as to what's going on in the log files: first two places to check:
  
  * check the CiviCRM log in /files/civicrm/ConfigAndLog/
  * check your php and/or php-fpm error log (location of that depends on your install one possible option is: /var/log/httpd/
  
  > **Comments:**
  > **username_2**: You can try the rc - release candidate right now: http://dist.civicrm.org/by-date/2016-08-30/4.7.11-rc/  
  > **username_0**: Sorry. Deleted my comment to post it as the answer. I edited the files listed in the github page's commits and I'm all fixed.  
  
  ---
  
  