TYPO3 Core

Sorry, but I can't reproduce the problem. I tried the following BE layout on master and it worked quite well

backend_layout {
    colCount = 2
    rowCount = 2
    rows {
    1 {
        columns {
            1 {
                name = Header
                colspan = 2
                colPos = 0
            }
         }
    }
    2 {
        columns {
            1 {
                name = Content
                colPos = 1
                }
            2 {
                name = Sidebar
                colPos = 2
               }
           }
       }
   }
}

Mint Linux, Apache 2.4.7, MySQL 5.5.43 here.

Maybe you could try the layout or somebody with a Windows System has to check.

Is your mysql running in strict mode? If so, please disable that.

Aha, the error appears due to a non-obvious configuration mistake.

When building the grid, the user is not forced to enter column numbers - which implies an automatic numbering or something.
It can be saved and used without further notification.

The above mentioned PHP Fatal Error is the result of such a columnnumber-less configuration.

Ok, so without colPos you get this error? Does this also happen with latest 7.4?

The error is reproducable when not a single colPos is given.

Crashes:

backend_layout {
    colCount = 2
    rowCount = 1
    rows {
        1 {
            columns {
                1 {
                    name = 0x0
                }
                2 {
                    name = 1x0
                }
            }
        }
    }
}

Does not crash:

backend_layout {
    colCount = 2
    rowCount = 1
    rows {
        1 {
            columns {
                1 {
                    name = 0x0
                    colPos = 1
                }
                2 {
                    name = 1x0
                }
            }
        }
    }
}

Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/45146

Patch set 3 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/45146