End of support for Microsoft Internet Explorer 9 in Pega 7.2.1
Valid from Pega Version 7.2.1
In accordance with Microsoft’s announcement to discontinue support for Internet Explorer 9, Pega 7.2.1 will not support Internet Explorer 9. You should not upgrade to Pega 7.2.1 if you are still using Internet Explorer 9. Otherwise, upgrade to Microsoft Internet Explorer 10 or later, or use Google Chrome, Apple Safari, or Mozilla Firefox, which support certain HTML5 and CSS3 standards not supported in Internet Explorer 9.
For more information about browser support, see the Platform Support Guide or contact Pegasystems Global Customer Support.
High number of busy waits when using Oracle SecureFiles
Valid from Pega Version 7.2.1
You might experience a high number of buffer busy waits when using Oracle SecureFiles for BLOB storage. An Oracle buffer busy wait occurs when a session cannot access a database block in the buffer cache, because another session is either reading the block into the buffer or changing the buffer. As a best practice, use Oracle 11.2.0.4 or later, because earlier versions have more problems with SecureFiles. In addition, to minimize the number of busy waits, set the hidden Oracle parameter _securefiles_concurrency_estimate to 50, and partition the table by using a composite range hash partition that is based on the pxCreateDateTime and pzInskey columns.
For more information, see Troubleshooting: High number of busy waits when using Oracle SecureFiles.
Discontinued support for multithreaded requestors
Valid from Pega Version 7.2.1
Multithreaded requestors are no longer supported in the Pega 7 Platform. Multithreading was previously specified by the prconfig setting initialization/allowMultiplePRThreads. If this setting is set to true when you upgrade to Pega 7.2.1, errors occur during the quiesce process.
Email approval and instantiation not supported on multitenant systems
Valid from Pega Version 7.2.1
The Enable email approval check box appears on the General tab of an approval step in Case Designer in multitenant systems. It also appears on the Approval shape in Designer Studio. In addition, in Designer Studio, the Settings tab in Case Designer displays the option to configure email instantiation. However, because configuring email listeners is not supported on multitenant systems, you cannot enable email approval or email instantiation.
Ignore locale settings requires refresh after server restarts
Valid from Pega Version 7.2.1
The Ignore locale check box in operator preferences is selected to display Designer Studio in U.S. English. After a server restarts, screens initially ignore this setting. When the screen is refreshed or reopened, the screen is rendered as expected.
Child case queries can be slow after upgrade
Valid from Pega Version 7.2.1
After upgrading, performance might be slow when you run queries on child cases for work tables that existed prior to the upgrade. This issue is often indicated by PEGA0005 (query time exceeded limit) alerts that can be correlated to these queries in the logs. To resolve the issue, add a database index to each of your work tables by using a multicolumn index on the pxCoverInsKey, pxObjClass, and pyStatusWork columns.
For more information, see Performance improvements for child case queries.
Flexbox-based dynamic layouts not supported for Android 4.4 and earlier
Valid from Pega Version 7.2.1
Flexbox-based dynamic layouts are not supported in Android 4.4 and earlier. When developing applications to be used on devices running Android 4.4 and earlier, use the inline-block layout mode for dynamic layouts.
MBean Javadocs download file
Valid from Pega Version 7.2.1
The Pega 7 Platform MBean Javadocs are no longer provided in the distribution image; however, you can download the 
MBeanJMXJavadoc.zip file that was previously provided in the distribution image.
You can also use JConsole, which is included with the Java Development Kit (JDK), to obtain MBean information. The JConsole MBean tab provides attributes, operations, notifications, and other information on all the MBeans that are registered with the MBean server.
Cannot send mobile push notifications when the Pega 7 Platform is hosted on WebSphere Application Server
Valid from Pega Version 7.2.1
Push notifications are not sent to Android or iOS mobile apps when the Pega 7 Platform is hosted on WebSphere Application Server.
Extract marker file not created at startup
Valid from Pega Version 7.2.1
The extract marker file (PegaRULES_Extract_Marker.txt) is not created at startup, because the rule utility libraries no longer need it. If you used to use the extract marker file to clear the static content file-based cache, to look up lists, or to control starting activities with web nodes, you can delete the contents of the PegaRULES temporary directory instead.