After an upgrade you find rendering issues with your portal theme, it can happen either with custom or standard themes and the theme appears distorted after login. I will go through some of the more common scenarios and resolutions.

Problem with rendering of SAP standard themes:

If you find that this is happening with standard SAP themes only then a good place to start with is kba 1911990- 'Enterprise Portal looks distorted after logon'. The resolution section contains 3 steps which should be executed in the order they appear (so first step 1, next 2 and finally 3). Its very important that after you implement each step to test the scenario again to see if the issue is resolved and themes are displaying correctly.

Problem with rendering of custom themes:

1. If its happening with your custom theme only, then firstly check kba2028300 - 'Custom portal theme distorted'.
2. If re-importing your custom theme doesn't help, then check to see if the issue is happening on one or some nodes only. If it is then check kba 2195099 - 'Portal theme is inconsistent after upgrade' to manually synchronize all server nodes.
3. Note 2197656 - 'Custom themes does not exist in all server nodes' includes a fix for this synchronization issue for later releases.
4. Is note 1738135 - 'Theme inconsistency in portal after 7.3 upgrade' applicable for your version?

If none of the above helps then reproduce the issue and check the default (kba 1596214) or logwatch (kba 1593107) trace files. For theme problems you should increase the severity of the following logging locations to ALL prior to reproducing the issue:

com.sap.portal.design: ALL

com.sap.portal.themes: ALL

com.sapportals.portal.design: ALL

com.sapportals.portal.style: ALL

Other notes:

• If you find the below exception in the traces after reproducing the issue, then apply kba 1959644 - 'Theme distorted after upgrade Error:LAFService.deleteTheme -> after deleteTheme'

#EP-PIN-TOL#sap.com/com.sap.portal.themes.lafservice#C0000A7EC319004B000
0022F000002B3#637167351000006463#sap.com/com.sap.portal.themes.designser
vicenotificationservice#com.sapportals.portal.prt.service.laf.LAFService
#Guest#0##A7E9808742F011E3B00B000025FA66F7#a7e9808742f011e3b00b000025fa6
6f7#a7e9808742f011e3b00b000025fa66f7#0#Application [53]#Plain##
LAFService.deleteTheme -> after deleteTheme.#

• Or if the following exception is found in the traces, then apply kba2044168- Customized portal theme not displayed after the upgrade
  

Error in starting application [sap.com/com.sap.portal.themes.designservicenotificationservice].
[EXCEPTION]
com.sap.engine.services.servlets_jsp.server.exceptions.WebDeploymentException: Error in starting application [sap.com/com.sap.portal.themes.designservicenotificationservice].
...
Caused by: com.sap.engine.services.servlets_jsp.server.exceptions.WebDeploymentException: Error occurred when invoking start methods of web container extensions for
...
Caused by: java.lang.NoSuchMethodError: com.sapportals.portal.prt.service.laf.ILookAndFeelService.getApplicationName(Lcom/sapportals/portal/prt/service/laf/ThemeType;)Ljava/lang/String;