We have upgraded from Appian 7.8 to 7.9 and now notice that each time when we op

Have you checked the version of your MySQL database to ensure it is supported?

RDBMS          Driver
MySQL 5.6.x
MySQL 5.6.22 with the InnoDB default engine is our reference platform, which is shown to provide optimal performance
Connector/J 5.1.34 (or later)

Oracle 12c R1          
Oracle Thin JDBC Driver for 12c R1

Oracle 11g R2          
Oracle Thin JDBC Driver for 11g R2

Microsoft SQL Server 2012          
2012: Microsoft JDBC SQL Server Driver 4.0

Microsoft SQL Server 2008          
2008: Microsoft JDBC SQL Server Driver 4.0 and 2.0

IBM DB2 UDB v9.7 for Linux, UNIX and Windows          
IBM DB2 JDBC Driver version 4.9.78

Could this be an issue with the browser/JRE? A few workstations seem to work. On my workstation (where it isn't working) I am running IE11 with JRE 1.8.0_45.

There is no local java runtime in the end user interface.. Try clearing your browser cache and relaunching the browser..

Thanks..that put me onto things. So like you recommended I just tried clearing everything out of my browser history/files/etc which I did using the standard IE "Delete History" function and restarted my browser. I still did get the error. However, as a further step I went into my windows "Temporary Internet Files" folder where there were still a bunch of files that IE didn't actually delete. I removed those and restarted and it now works. I explained this in detail only so others won't miss any particulars.

Thanks for your help!

No problem.. I suspect what happened is that you tried to access the design environment maybe when some services were still initializing or not fully available.. That resulted in the first error.. which then was cached.. so even though it was working.. the last cache still had the error.. it probably would have naturally resolved as the cache expired and updated over the next 24 hours..

@robbier, I too faced the same issue today. Found this post. Thank you! I have been struggling to get Appian 7.9 installed since 4-5 hours. It finally is installed.